Cleanup Widevine PSSH

[ftyp]

https://tools.axinom.com/decoders/PsshBox

Remove deprecated Algorithm field 1 which should not be used conjunction with Protection Scheme field 9

If backward compatibility is needed please consider using the Algorithm field only for CENC instead, e.g.

if encryption_scheme == 'cenc':
    protobuf_fields.append((1, 1))
else:
    four_cc = struct.unpack('>I', encryption_scheme.encode('ascii'))[0]
    protobuf_fields.append((9, four_cc))