Update security_admin.py

Change type hints for get_running_userid to Union[str, None]

Signed-off-by: Elijah Swift <elijah.swift@ibm.com>

pyracf/common/security_admin.py

@@ -96,7 +96,7 @@ def set_running_userid(self, userid: Union[str, None]) -> None:
             raise UserIdError(userid)
         self.__running_userid = userid.upper()
 
-    def get_running_userid(self) -> None:
+    def get_running_userid(self) -> Union[str, None]:
         if isinstance(self.__running_userid, str):
             return self.__running_userid.lower()
         return self.__running_userid