Change installation command to fit with new github protocol

[tommy307507]

According to the new github security update, the old git:// channel is permantly disabled on March 15.
https://github.blog/2021-09-01-improving-git-protocol-security-github/

The new command should be using the https:// encrypted protocol. i.e. changing from git:// to https:// will fix it. Else it will throw and error and point to the website above.
pip install git+https://github.com/Thann/play-with-mpv.git --user

The error that it'll throw using old command:
The unauthenticated git protocol on port 9418 is no longer supported.
Please see https://github.blog/2021-09-01-improving-git-protocol-security-github/ for more information.

[SonaliBendre]

pip3 install git+https://github.com/Thann/play-with-mpv.git --user