Move setuptools._path.StrPath out of the if TYPE_CHECKING (Python 3.9+) (#4722)

Author: abravalheri

setuptools/_path.py

@@ -10,10 +10,8 @@
 if TYPE_CHECKING:
     from typing_extensions import TypeAlias
 
-    StrPath: TypeAlias = Union[str, os.PathLike[str]]  #  Same as _typeshed.StrPath
-else:
-    # Python 3.8 support
-    StrPath: TypeAlias = Union[str, os.PathLike]
+
+StrPath: TypeAlias = Union[str, os.PathLike[str]]  #  Same as _typeshed.StrPath
 
 
 def ensure_directory(path):