Add async to functions.

fetchYoutubeSubtitle.py

@@ -10,7 +10,7 @@ def getVttUrlFromSubtitles(item, lang='en', vttType="vtt"):
             return item.get("url")
     return None
 
-def getSubtitle(url: str, lang: Optional[str] = 'en', vttType="vtt") -> Optional[str]:
+async def getSubtitle(url: str, lang: Optional[str] = 'en', vttType="vtt") -> Optional[str]:
     ydl_opts = {
         "writesubtitles": True,
         "allsubtitles": True,
@@ -31,7 +31,7 @@ def getSubtitle(url: str, lang: Optional[str] = 'en', vttType="vtt") -> Optional
                 return subtitle.read().decode()
     return None
 
-def fetchSubtitleUrls(url: str) -> json:
+async def fetchSubtitleUrls(url: str) -> json:
     ydl_opts = {
         "writesubtitles": True,
         "allsubtitles": True,