Mark pyRFC3339 as completed (#9233)

stubs/pyRFC3339/METADATA.toml

@@ -1 +1,4 @@
 version = "1.1"
+
+[tool.stubtest]
+ignore_missing_stub = false

stubs/pyRFC3339/pyrfc3339/utils.pyi

@@ -1,10 +1,13 @@
+from _typeshed import Self
 from datetime import datetime, timedelta, tzinfo
+from typing import Any
 
 class FixedOffset(tzinfo):
     def __init__(self, hours: float, minutes: float) -> None: ...
     def dst(self, dt: datetime | None) -> timedelta: ...
     def utcoffset(self, dt: datetime | None) -> timedelta: ...
     def tzname(self, dt: datetime | None) -> str: ...
+    def __deepcopy__(self: Self, memo: dict[int, Any]) -> Self: ...
 
 def timedelta_seconds(td: timedelta) -> int: ...
 def timezone(utcoffset: float) -> str: ...