tidy up ruff check

Author: davemssavage

tests/shared/test_session.py

@@ -165,7 +165,7 @@ async def make_request(client_session: ClientSession):
         nonlocal ev_cancelled
         try:
             await client_session.call_tool("slow_tool", cancellable=False)
-        except McpError as e:
+        except McpError:
             pytest.fail("Request should not have been cancelled")
 
     async with create_connected_server_and_client_session(