net/rclone-browser: Change to new upstream fork

The previous GitHub repository is now labelled as inactive and
unmaintained [1].

This new fork [2] has been around since August 2019, has fixed many bugs
and added new features (even mounting remotes in FreeBSD).

[1] https://github.com/mmozeiko/RcloneBrowser
[2] https://github.com/kapitainsky/RcloneBrowser

Reported by: Dariusz Bogdanski <dariuszb@me.com> (upstream maintainer)