Add typing for TarFile._extract_member method (#5841)

Refs: #2673

Author: jdufresne

stdlib/tarfile.pyi

@@ -264,6 +264,9 @@ class TarFile:
     def extract(
         self, member: Union[str, TarInfo], path: StrOrBytesPath = ..., set_attrs: bool = ..., *, numeric_owner: bool = ...
     ) -> None: ...
+    def _extract_member(
+        self, tarinfo: TarInfo, targetpath: str, set_attrs: bool = ..., numeric_owner: bool = ...
+    ) -> None: ...  # undocumented
     def extractfile(self, member: Union[str, TarInfo]) -> Optional[IO[bytes]]: ...
     def makedir(self, tarinfo: TarInfo, targetpath: StrOrBytesPath) -> None: ...  # undocumented
     def makefile(self, tarinfo: TarInfo, targetpath: StrOrBytesPath) -> None: ...  # undocumented