[vk] remove assert statement

youtube_dl/extractor/vk.py

@@ -600,7 +600,6 @@ class VKWallPostIE(VKBaseIE):
         if 'audio_api_unavailable' in mask_url:
             extra = mask_url.split('?extra=')[1].split('#')
             func, base = self._decode(extra[1]).split(chr(11))
-            assert (func == 'i')
             mask_url = list(self._decode(extra[0]))
             url_len = len(mask_url)
             indexes = [None] * url_len