Fix __class_getitem__ to be positional-only

Author: ankith26

buildconfig/stubs/pygame/sprite.pyi

@@ -144,7 +144,7 @@ _TDirtySprite = TypeVar("_TDirtySprite", bound=_DirtySpriteSupportsGroup)
 class AbstractGroup(Generic[_TSprite]):
     spritedict: dict[_TSprite, Optional[Union[FRect, Rect]]]
     lostsprites: list[Union[FRect, Rect]]
-    def __class_getitem__(cls, generic: Any) -> types.GenericAlias: ...
+    def __class_getitem__(cls, generic: Any, /) -> types.GenericAlias: ...
     def __init__(self) -> None: ...
     def __len__(self) -> int: ...
     def __iter__(self) -> Iterator[_TSprite]: ...