Fix errors detected by Ruff (#3918)

### What problem does this PR solve?

Fix errors detected by Ruff

### Type of change

- [x] Refactoring

agent/test/client.py

@@ -43,6 +43,7 @@ if __name__ == '__main__':
         else:
             print(ans["content"])
 
-        if DEBUG: print(canvas.path)
+        if DEBUG:
+            print(canvas.path)
         question = input("\n==================== User =====================\n> ")
         canvas.add_user_input(question)