Fix 'dict_keys' object has no attribute 'length'

fetchYoutubeSubtitle.py

@@ -42,7 +42,7 @@ def fetchSubtitleUrls(url: str) -> json:
         info_dict = ydl.extract_info(url, download=False)
         if info_dict.get("subtitles"):
             langs = info_dict.get("subtitles").keys()
-            if not (langs.length == 1 and "live_chat" in langs):
+            if not (len(langs) == 1 and "live_chat" in langs):
                 return info_dict.get("subtitles")
             if info_dict.get("automatic_captions"):
                 return info_dict.get("automatic_captions")