Bug#995068: gnome-games-app: Rename to highscore

[Jeremy Bicha]

Source: gnome-games-app
Version: 40.0-3

gnome-games-app appears to have been renamed to highscore so we should
rename our Debian packaging to match, once there is a new release.

I'm filing this bug as a reminder because our debian/watch won't pick
up the new release automatically.

https://gitlab.gnome.org/World/highscore

Background is at https://gitlab.gnome.org/Archive/gnome-games/-/issues/243

Thanks,
Jeremy Bicha