Akuli and srittau: Remove Python 2 branches from Python 3 stubs (#5461)

* run script and do some manual changes (Akuli)

* do the whole thing manually (srittau)

* merge changes (Akuli)

Co-authored-by: Sebastian Rittau <srittau@rittau.biz>

stdlib/readline.pyi

@@ -1,4 +1,3 @@
-import sys
 from _typeshed import AnyPath
 from typing import Callable, Optional, Sequence
 
@@ -12,10 +11,7 @@ def insert_text(__string: str) -> None: ...
 def redisplay() -> None: ...
 def read_history_file(__filename: Optional[AnyPath] = ...) -> None: ...
 def write_history_file(__filename: Optional[AnyPath] = ...) -> None: ...
-
-if sys.version_info >= (3, 5):
-    def append_history_file(__nelements: int, __filename: Optional[AnyPath] = ...) -> None: ...
-
+def append_history_file(__nelements: int, __filename: Optional[AnyPath] = ...) -> None: ...
 def get_history_length() -> int: ...
 def set_history_length(__length: int) -> None: ...
 def clear_history() -> None: ...
@@ -24,10 +20,7 @@ def get_history_item(__index: int) -> str: ...
 def remove_history_item(__pos: int) -> None: ...
 def replace_history_item(__pos: int, __line: str) -> None: ...
 def add_history(__string: str) -> None: ...
-
-if sys.version_info >= (3, 6):
-    def set_auto_history(__enabled: bool) -> None: ...
-
+def set_auto_history(__enabled: bool) -> None: ...
 def set_startup_hook(__function: Optional[Callable[[], None]] = ...) -> None: ...
 def set_pre_input_hook(__function: Optional[Callable[[], None]] = ...) -> None: ...
 def set_completer(__function: _CompleterT = ...) -> None: ...