Always use _typeshed.Self, where applicable (#6880)

* Always use `_typeshed.Self`, where applicable

* Revert changes to `google-cloud-ndb` (ambiguous)

* Remove empty line added by script

* Revert changes to `stubs/python-dateutil/dateutil/relativedelta.pyi`

* Manually add a few more that the script missed

* Improve `filelock` annotation

Source code here: 79ec7b2826/src/filelock/_api.py (L207)

* Improve `opentracing/scope` annotation

Source code here: 3e1d357a34/opentracing/scope.py (L71)

* Improve `redis/client` stub

Source code here: 15f315a496/redis/client.py (L1217)

* Improve `redis/lock` annotation

Source code here: 15f315a496/redis/lock.py (L155)

* Improve `requests/models` annotation

Source code here: d718e75383/requests/models.py (L653)

stdlib/datetime.pyi

@@ -1,9 +1,9 @@
 import sys
+from _typeshed import Self
 from time import struct_time
 from typing import ClassVar, NamedTuple, NoReturn, SupportsAbs, TypeVar, overload
 from typing_extensions import final
 
-_S = TypeVar("_S")
 _D = TypeVar("_D", bound=date)
 
 MINYEAR: int
@@ -36,19 +36,19 @@ class date:
     min: ClassVar[date]
     max: ClassVar[date]
     resolution: ClassVar[timedelta]
-    def __new__(cls: type[_S], year: int, month: int, day: int) -> _S: ...
+    def __new__(cls: type[Self], year: int, month: int, day: int) -> Self: ...
     @classmethod
-    def fromtimestamp(cls: type[_S], __timestamp: float) -> _S: ...
+    def fromtimestamp(cls: type[Self], __timestamp: float) -> Self: ...
     @classmethod
-    def today(cls: type[_S]) -> _S: ...
+    def today(cls: type[Self]) -> Self: ...
     @classmethod
-    def fromordinal(cls: type[_S], __n: int) -> _S: ...
+    def fromordinal(cls: type[Self], __n: int) -> Self: ...
     if sys.version_info >= (3, 7):
         @classmethod
-        def fromisoformat(cls: type[_S], __date_string: str) -> _S: ...
+        def fromisoformat(cls: type[Self], __date_string: str) -> Self: ...
     if sys.version_info >= (3, 8):
         @classmethod
-        def fromisocalendar(cls: type[_S], year: int, week: int, day: int) -> _S: ...
+        def fromisocalendar(cls: type[Self], year: int, week: int, day: int) -> Self: ...
     @property
     def year(self) -> int: ...
     @property
@@ -67,10 +67,10 @@ class date:
     def __ge__(self, __other: date) -> bool: ...
     def __gt__(self, __other: date) -> bool: ...
     if sys.version_info >= (3, 8):
-        def __add__(self: _S, __other: timedelta) -> _S: ...
-        def __radd__(self: _S, __other: timedelta) -> _S: ...
+        def __add__(self: Self, __other: timedelta) -> Self: ...
+        def __radd__(self: Self, __other: timedelta) -> Self: ...
         @overload
-        def __sub__(self: _D, __other: timedelta) -> _D: ...
+        def __sub__(self: Self, __other: timedelta) -> Self: ...
         @overload
         def __sub__(self, __other: datetime) -> NoReturn: ...
         @overload
@@ -98,7 +98,7 @@ class time:
     max: ClassVar[time]
     resolution: ClassVar[timedelta]
     def __new__(
-        cls: type[_S],
+        cls: type[Self],
         hour: int = ...,
         minute: int = ...,
         second: int = ...,
@@ -106,7 +106,7 @@ class time:
         tzinfo: _tzinfo | None = ...,
         *,
         fold: int = ...,
-    ) -> _S: ...
+    ) -> Self: ...
     @property
     def hour(self) -> int: ...
     @property
@@ -127,7 +127,7 @@ class time:
     def isoformat(self, timespec: str = ...) -> str: ...
     if sys.version_info >= (3, 7):
         @classmethod
-        def fromisoformat(cls: type[_S], __time_string: str) -> _S: ...
+        def fromisoformat(cls: type[Self], __time_string: str) -> Self: ...
     def strftime(self, __format: str) -> str: ...
     def __format__(self, __fmt: str) -> str: ...
     def utcoffset(self) -> timedelta | None: ...
@@ -152,7 +152,7 @@ class timedelta(SupportsAbs[timedelta]):
     max: ClassVar[timedelta]
     resolution: ClassVar[timedelta]
     def __new__(
-        cls: type[_S],
+        cls: type[Self],
         days: float = ...,
         seconds: float = ...,
         microseconds: float = ...,
@@ -160,7 +160,7 @@ class timedelta(SupportsAbs[timedelta]):
         minutes: float = ...,
         hours: float = ...,
         weeks: float = ...,
-    ) -> _S: ...
+    ) -> Self: ...
     @property
     def days(self) -> int: ...
     @property
@@ -199,7 +199,7 @@ class datetime(date):
     max: ClassVar[datetime]
     resolution: ClassVar[timedelta]
     def __new__(
-        cls: type[_S],
+        cls: type[Self],
         year: int,
         month: int,
         day: int,
@@ -210,7 +210,7 @@ class datetime(date):
         tzinfo: _tzinfo | None = ...,
         *,
         fold: int = ...,
-    ) -> _S: ...
+    ) -> Self: ...
     @property
     def hour(self) -> int: ...
     @property
@@ -227,26 +227,26 @@ class datetime(date):
     # but it is named "timestamp" in the C implementation and "t" in the Python implementation,
     # so it is only truly *safe* to pass it as a positional argument.
     @classmethod
-    def fromtimestamp(cls: type[_S], __timestamp: float, tz: _tzinfo | None = ...) -> _S: ...
+    def fromtimestamp(cls: type[Self], __timestamp: float, tz: _tzinfo | None = ...) -> Self: ...
     @classmethod
-    def utcfromtimestamp(cls: type[_S], __t: float) -> _S: ...
+    def utcfromtimestamp(cls: type[Self], __t: float) -> Self: ...
     if sys.version_info >= (3, 8):
         @classmethod
-        def now(cls: type[_S], tz: _tzinfo | None = ...) -> _S: ...
+        def now(cls: type[Self], tz: _tzinfo | None = ...) -> Self: ...
     else:
         @overload
         @classmethod
-        def now(cls: type[_S], tz: None = ...) -> _S: ...
+        def now(cls: type[Self], tz: None = ...) -> Self: ...
         @overload
         @classmethod
         def now(cls, tz: _tzinfo) -> datetime: ...
     @classmethod
-    def utcnow(cls: type[_S]) -> _S: ...
+    def utcnow(cls: type[Self]) -> Self: ...
     @classmethod
     def combine(cls, date: _date, time: _time, tzinfo: _tzinfo | None = ...) -> datetime: ...
     if sys.version_info >= (3, 7):
         @classmethod
-        def fromisoformat(cls: type[_S], __date_string: str) -> _S: ...
+        def fromisoformat(cls: type[Self], __date_string: str) -> Self: ...
     def timestamp(self) -> float: ...
     def utctimetuple(self) -> struct_time: ...
     def date(self) -> _date: ...
@@ -266,7 +266,7 @@ class datetime(date):
         fold: int = ...,
     ) -> datetime: ...
     if sys.version_info >= (3, 8):
-        def astimezone(self: _S, tz: _tzinfo | None = ...) -> _S: ...
+        def astimezone(self: Self, tz: _tzinfo | None = ...) -> Self: ...
     else:
         def astimezone(self, tz: _tzinfo | None = ...) -> datetime: ...
     def ctime(self) -> str: ...
@@ -282,7 +282,7 @@ class datetime(date):
     def __gt__(self, __other: datetime) -> bool: ...  # type: ignore[override]
     if sys.version_info >= (3, 8):
         @overload  # type: ignore[override]
-        def __sub__(self: _D, __other: timedelta) -> _D: ...
+        def __sub__(self: Self, __other: timedelta) -> Self: ...
         @overload
         def __sub__(self: _D, __other: _D) -> timedelta: ...
     else: