[pathlib] Deprecate PurePath.is_reserved (#14478)

Source: python/cpython#95486
Docs: https://docs.python.org/3.14/library/pathlib.html#pathlib.PurePath.is_reserved

Author: donbarbos

stdlib/pathlib/__init__.pyi

@@ -67,7 +67,14 @@ class PurePath(PathLike[str]):
     def as_posix(self) -> str: ...
     def as_uri(self) -> str: ...
     def is_absolute(self) -> bool: ...
-    def is_reserved(self) -> bool: ...
+    if sys.version_info >= (3, 13):
+        @deprecated(
+            "Deprecated since Python 3.13; will be removed in Python 3.15. "
+            "Use `os.path.isreserved()` to detect reserved paths on Windows."
+        )
+        def is_reserved(self) -> bool: ...
+    else:
+        def is_reserved(self) -> bool: ...
     if sys.version_info >= (3, 14):
         def is_relative_to(self, other: StrPath) -> bool: ...
     elif sys.version_info >= (3, 12):
@@ -163,7 +170,6 @@ class Path(PurePath):
     def mkdir(self, mode: int = 0o777, parents: bool = False, exist_ok: bool = False) -> None: ...
 
     if sys.version_info >= (3, 14):
-
         @property
         def info(self) -> PathInfo: ...
         @overload