fix: benchmark annotations

benchmarks/bench/fixed_qps_latency.py

@@ -8,6 +8,8 @@
 sends requests at a steady rate to measure realistic latency impact.
 """
 
+from __future__ import annotations
+
 import json
 import os
 import subprocess

benchmarks/bench/realistic_workload.py

@@ -9,6 +9,8 @@
 These simulate production APIs that do actual work (I/O, validation, processing).
 """
 
+from __future__ import annotations
+
 import json
 import os
 import subprocess

benchmarks/bench/sdk_sampling_rates.py

@@ -1,6 +1,8 @@
 #!/usr/bin/env python3
 """Benchmark: SDK with different sampling rates."""
 
+from __future__ import annotations
+
 import os
 import shutil
 import sys