BOM causes MalformedFileError in from_buffer

[Frenzie]

If you use the following sample file with .from_buffer() you receive a MalformedFileError error.

srt-with-bom.zip

webvtt.from_buffer(io.StringIO(caption_file_from_upload.read().decode('utf-8')), "srt")

It may not be a bug because it's solved by using:

webvtt.from_buffer(io.StringIO(caption_file_from_upload.read().decode('utf-8-sig')), "srt")

See https://docs.python.org/3/library/codecs.html#encodings-and-unicode

But it doesn't happen with .from_srt(), which strips out the BOM by itself.