Minor modification for creating cards with Memento (an excellent video player based on MPV)

[wandero]

When using Local Audio Server in conjunction with Memento (an excellent video player based on MPV) for card creation, the service was ineffective due to the lack of the Content-length parameter.

Following guidance from @ripose-jp, I modified the server.py code to resolve the issue and hope this modification can be incorporated into the plugin to benefit more users:

Added import os
#after self.send_header("Content-type", mime_type) Appended the line
self.send_header('Content-length', str(os.stat(audio_file).st_size))

The plugin is very useful, thanks a lot