Updated mypy failures

Author: rajeshvelicheti

src/a2a/server/apps/rest/rest_adapter.py

@@ -105,7 +105,7 @@ async def handle_get_agent_card(self, request: Request) -> JSONResponse:
     @rest_error_handler
     async def handle_authenticated_agent_card(
         self, request: Request
-    ) -> JSONResponse: # type: ignore[return-value]
+    ) -> JSONResponse:  # type: ignore[return-value]
         """Hook for per credential agent card response.
 
         If a dynamic card is needed based on the credentials provided in the request