Add support for GNOME projects

[rffontenelle]

The versions for GNOME software are provided and accessible in these URLs:

https://ftp.gnome.org/pub/GNOME/sources/%s/cache.json
http://ftp.gnome.org/pub/GNOME/sources/%s/cache.json
ftp://ftp.gnome.org/pub/GNOME/sources/%s/cache.json
https://download.gnome.org/sources/%s/cache.json

where %s is the name of the software (e.g. gnome-shell)

If possible, please consider implementing support for them.

[sum01]

@rffontenelle Is this still relevant now that Gnome moved everything to Gitlab?

[rffontenelle]

I believe it is. Of course some official packages set to a specific commit from Gitlab as source, but many others use the official release tarball repositories: ftp://ftp.gnome.org and https://download.gnome.org