fix: correct MCPClient.__exit__ and stop() type annotations

Fixes #2247

Author: cogwirrel

src/strands/tools/mcp/mcp_client.py

@@ -178,7 +178,12 @@ def __enter__(self) -> "MCPClient":
         """
         return self.start()
 
-    def __exit__(self, exc_type: BaseException, exc_val: BaseException, exc_tb: TracebackType) -> None:
+    def __exit__(
+        self,
+        exc_type: type[BaseException] | None,
+        exc_val: BaseException | None,
+        exc_tb: TracebackType | None,
+    ) -> None:
         """Context manager exit point that cleans up resources."""
         self.stop(exc_type, exc_val, exc_tb)
 
@@ -318,7 +323,7 @@ def remove_consumer(self, consumer_id: Any, **kwargs: Any) -> None:
 
     # MCP-specific methods
 
-    def stop(self, exc_type: BaseException | None, exc_val: BaseException | None, exc_tb: TracebackType | None) -> None:
+    def stop(self, exc_type: type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None) -> None:
         """Signals the background thread to stop and waits for it to complete, ensuring proper cleanup of all resources.
 
         This method is defensive and can handle partial initialization states that may occur