Add [dmm.com] support

[MarioSonicU]

When I was trying to get the keys form a video I purchased on the site, I got this error

Input MPD URL: https://vmdash-cenc.akamaized.net/tw-cenc-gnr/k20160903034215/cp-wxtg04/047/239/047239028000_4096.mpd License URL: https://api-p.videomarket.jp/v3/api/play/keyissue

PSSH obtained. AAAAjHBzc2gAAAAA7e+LqXnWSs6jyCfc1R0h7QAAAGwIARIQ1HgYlcEoTYe4OPg/xIKD/CJPeyJ2ZW5kb3JfY29kZSI6InZpZGVvbWFya2V0IiwicHJvZHVjdF9jb2RlIjoiZDQ3ODE4OTVjMTI4NGQ4N2I4MzhmODNmYzQ4MjgzZmMifSoFU0RfSEQ=

license response status: <Response [400]> server reports: {"status":{"code":400,"message":"PlayToken has failed."},"errorInfo":{"code":"PT20002","notice":"作品を 再生するための認証ができませんでした。PT20002"}} server did not issue license, make sure you have correctly pasted all the required headers in the headers.py. Also check json/raw params of POST request.

The japanese part roughly translates to: "Could not authenticate to play the work."

Any reasons as to why this is?

[huliad2022]

I suggest you read the author's updated instructions first （README.md）