revert some changes to make CI pass

Author: guoci

stdlib/multiprocessing/managers.pyi

@@ -192,8 +192,6 @@ class BaseListProxy(BaseProxy, MutableSequence[_T]):
     def count(self, value: _T, /) -> int: ...
     def insert(self, index: SupportsIndex, object: _T, /) -> None: ...
     def remove(self, value: _T, /) -> None: ...
-    if sys.version_info >= (3, 14):
-        def copy(self) -> list[_T]: ...
     # Use BaseListProxy[SupportsRichComparisonT] for the first overload rather than [SupportsRichComparison]
     # to work around invariance
     @overload