chore: make typing more appropriate for a method

Signed-off-by: Norbert Biczo <[email protected]>

Author: pyrooka

ibm_cloud_sdk_core/detailed_response.py

@@ -65,7 +65,7 @@ def get_headers(self) -> Optional[dict]:
         """
         return self.headers
 
-    def get_status_code(self) -> int:
+    def get_status_code(self) -> Union[int, None]:
         """The HTTP status code of the service request.
 
         Returns: