Fix lint error: Remove unused config variable

- Remove unused variable assignment that was triggering F841 lint error
- Simply validate the config_dict without capturing the result

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: robtaylor

chipflow_lib/__init__.py

@@ -49,7 +49,7 @@ def _parse_config_file(config_file):
 
     try:
         # Validate with Pydantic
-        config = Config.model_validate(config_dict)
+        Config.model_validate(config_dict)  # Just validate the config_dict
         return config_dict  # Return the original dict for backward compatibility
     except ValidationError as e:
         # Format Pydantic validation errors in a user-friendly way