Avoid computing higher temperatures on no_speech segments (#225)

Port commit https://github.com/openai/whisper/commit/e334ff141d5444fbf6904edaaf408e5b0b416fe8

faster_whisper/transcribe.py

@@ -649,6 +649,12 @@ class WhisperModel:
                     options.log_prob_threshold,
                 )
 
+            if (
+                options.no_speech_threshold is not None
+                and result.no_speech_prob > options.no_speech_threshold
+            ):
+                needs_fallback = False  # silence
+
             if not needs_fallback:
                 break