test(transcription): annotate the new passthrough test's locals as Final

tests/unit/proxy/pass_through_endpoints/llm_provider_handlers/test_transcribe_passthrough_logging_handler.py

@@ -5,6 +5,7 @@ import struct
 import wave
 from datetime import datetime
 from pathlib import Path
+from typing import Final
 from unittest.mock import MagicMock
 
 import httpx
@@ -455,10 +456,10 @@ class TestMediaFileSeconds:
         assert media_file_seconds(media) == pytest.approx(1.5)
 
     def test_flac_that_does_not_state_its_length_yields_no_duration(self, tmp_path: Path):
-        streaminfo = (
+        streaminfo: Final = (
             struct.pack(">HH", 4096, 4096) + bytes(6) + ((16000 << 44) | (15 << 36)).to_bytes(8, "big") + bytes(16)
         )
-        media = tmp_path / "a.flac"
+        media: Final = tmp_path / "a.flac"
         _ = media.write_bytes(b"fLaC" + b"\x80" + len(streaminfo).to_bytes(3, "big") + streaminfo)
 
         assert media_file_seconds(media) is None