Avoid using new _typeshed protocol in pkg_resources for now (#11909)

stubs/setuptools/pkg_resources/__init__.pyi

@@ -1,7 +1,6 @@
 import types
 import zipimport
 from _typeshed import Incomplete, StrPath, Unused
-from _typeshed.importlib import LoaderProtocol
 from collections.abc import Callable, Generator, Iterable, Iterator, Sequence
 from io import BytesIO
 from itertools import chain
@@ -13,6 +12,10 @@ from zipfile import ZipInfo
 
 from ._vendored_packaging import requirements as packaging_requirements, version as packaging_version
 
+# TODO: Use _typeshed.importlib.LoaderProtocol once mypy has included it in its vendored typeshed
+class _LoaderProtocol(Protocol):
+    def load_module(self, fullname: str, /) -> types.ModuleType: ...
+
 _T = TypeVar("_T")
 _D = TypeVar("_D", bound=Distribution)
 _NestedStr: TypeAlias = str | Iterable[_NestedStr]
@@ -360,7 +363,7 @@ def evaluate_marker(text: str, extra: Incomplete | None = None) -> bool: ...
 class NullProvider:
     egg_name: str | None
     egg_info: str | None
-    loader: LoaderProtocol | None
+    loader: _LoaderProtocol | None
     module_path: str | None
 
     def __init__(self, module: _ModuleLike) -> None: ...