fix linting issues

Author: alvinkam2001

src/agentex/lib/core/tracing/processors/sgp_tracing_processor.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from typing import override
 
 import scale_gp_beta.lib.tracing as tracing

src/agentex/lib/core/tracing/processors/tracing_processor_interface.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import asyncio
 from abc import ABC, abstractmethod