How about using a bot to guard the pull request can be apply? like rust compiler does.

[Yonggang Luo]

Peter can @bots try to apply pull request, if pull request apply and all ci
tests passed, then the bot automatically merge the pull request and push to
the mirrors.
We even doesn't need gitlab or other things, only need the bot to monitor
the instruction from Peter.

-- 
         此致
礼
罗勇刚
Yours
    sincerely,
Yonggang Luo