chore: Annotate the type of transcription parameter in _has_non_empty_transcription_text

Co-authored-by: Xiang (Sean) Zhou <seanzhougoogle@google.com>
PiperOrigin-RevId: 853880336

src/google/adk/runners.py

@@ -78,7 +78,9 @@ def _is_transcription(event: Event) -> bool:
   )
 
 
-def _has_non_empty_transcription_text(transcription) -> bool:
+def _has_non_empty_transcription_text(
+    transcription: types.Transcription,
+) -> bool:
   return bool(
       transcription and transcription.text and transcription.text.strip()
   )