make RFont._save path type hint compatible with superclass

Author: adbac

Lib/fontParts/fontshell/font.py

@@ -55,7 +55,7 @@ def _get_path(self, **kwargs: Any) -> str | None:
 
     def _save(
         self,
-        path: str | None = None,
+        path: str | os.PathLike | None = None,
         showProgress: bool = False,
         formatVersion: int | None = None,
         fileStructure: str | None = None,