Fix import order (pre-commit auto-fix)

Author: certainly-param

pydantic_ai_slim/pydantic_ai/usage.py

@@ -1,7 +1,7 @@
 from __future__ import annotations as _annotations
 
-import threading
 import dataclasses
+import threading
 from copy import copy
 from dataclasses import dataclass, fields
 from typing import Annotated, Any