[stdlib] Align Traversable joinpath and __truediv__ with CPython

The CPython implementation accepts `str | os.PathLike[str]`, typeshed
only accepts `str`.

CPython 3.13 implementations:
https://github.com/python/cpython/blob/59f247e43bc93c607a5793c220bcaafb712cf542/Lib/importlib/resources/abc.py#L104
https://github.com/python/cpython/blob/59f247e43bc93c607a5793c220bcaafb712cf542/Lib/importlib/resources/abc.py#L129

Author: dcbaker

stdlib/importlib/readers.pyi

@@ -52,7 +52,7 @@ if sys.version_info >= (3, 10):
         def is_file(self) -> Literal[False]: ...
 
         if sys.version_info >= (3, 12):
-            def joinpath(self, *descendants: str) -> abc.Traversable: ...
+            def joinpath(self, *descendants: StrPath) -> abc.Traversable: ...
         elif sys.version_info >= (3, 11):
             def joinpath(self, child: str) -> abc.Traversable: ...  # type: ignore[override]
         else:

stdlib/importlib/resources/abc.pyi

@@ -4,6 +4,8 @@ from collections.abc import Iterator
 from io import BufferedReader
 from typing import IO, Any, Literal, Protocol, overload, runtime_checkable
 
+from _typeshed import StrPath
+
 if sys.version_info >= (3, 11):
     class ResourceReader(metaclass=ABCMeta):
         @abstractmethod
@@ -24,7 +26,7 @@ if sys.version_info >= (3, 11):
         @abstractmethod
         def iterdir(self) -> Iterator[Traversable]: ...
         @abstractmethod
-        def joinpath(self, *descendants: str) -> Traversable: ...
+        def joinpath(self, *descendants: StrPath) -> Traversable: ...
 
         # The documentation and runtime protocol allows *args, **kwargs arguments,
         # but this would mean that all implementers would have to support them,
@@ -38,7 +40,7 @@ if sys.version_info >= (3, 11):
         @property
         @abstractmethod
         def name(self) -> str: ...
-        def __truediv__(self, child: str, /) -> Traversable: ...
+        def __truediv__(self, child: StrPath, /) -> Traversable: ...
         @abstractmethod
         def read_bytes(self) -> bytes: ...
         @abstractmethod