Update speech_transformers.py

Author: dvh312

ffsubsync/speech_transformers.py

@@ -367,6 +367,8 @@ def fit(self, fname: str, *_) -> "VideoSpeechTransformer":
                 "1",
                 "-acodec",
                 "pcm_s16le",
+                "-af",
+                "aresample=async=1",
                 "-ar",
                 str(self.frame_rate),
                 "-",