Remove warning on deepcopy which gets triggered for some async knowledge bases (#2659)

## Summary

Sometimes knowledge base fails to deepcopy, but copy succeeds.

## Type of change

- [ ] Bug fix (If applicable, issue number: #____)
- [ ] New feature
- [ ] Breaking change
- [ ] Improvement
- [ ] Model update
- [ ] Other: _____________________

---

## Checklist

- [ ] Code complies with style guidelines
- [ ] Ran format/validation scripts (`./scripts/format.sh` and
`./scripts/validate.sh`)
- [ ] Self-review completed
- [ ] Documentation updated (comments, docstrings)
- [ ] Examples and guides: Relevant cookbook examples have been included
or updated (if applicable)
- [ ] Tested in clean environment
- [ ] Tests added/updated (if applicable)

---

## Additional Notes

Add any important context (deployment instructions, screenshots,
security considerations, etc.)

Author: dirkbrnd

libs/agno/agno/agent/agent.py

@@ -2619,8 +2619,7 @@ def _deep_copy_field(self, field_name: str, field_value: Any) -> Any:
         elif isinstance(field_value, BaseModel):
             try:
                 return field_value.model_copy(deep=True)
-            except Exception as e:
-                log_warning(f"Failed to deepcopy field: {field_name} - {e}")
+            except Exception:
                 try:
                     return field_value.model_copy(deep=False)
                 except Exception as e: