checkMetadata: support WebM containers

check_metadata/check_metadata.py

@@ -27,7 +27,7 @@ class MediaFile:
     duration: int #in sec
 
 def supported_file_extension(filename):
-    if filename.endswith('.mp4') or filename.endswith('.mkv') or filename.endswith('.m4v'):
+    if filename.endswith('.mp4') or filename.endswith('.mkv') or filename.endswith('.webm') or filename.endswith('.m4v'):
         return True
     return False