Add "get-latest-version" util command

[hadess]

This gets the latest version specified in an appdata file, which, combined with utilities such as check-news.sh1, can be used to check whether the date specified in the appdata's release information is correct.

See https://gitlab.gnome.org/GNOME/evince/-/issues/1950

[hughsie]

This makes total sense, but I think it should be added to the https://github.com/ximion/appstream project instead; appstream-glib is in heavy maintenance mode now and we're not really taking on new features. I think most things have been ported, or am porting to the newer libappstream library maintained by @ximion

[hadess]

This makes total sense, but I think it should be added to the https://github.com/ximion/appstream project instead; appstream-glib is in heavy maintenance mode now and we're not really taking on new features. I think most things have been ported, or am porting to the newer libappstream library maintained by @ximion

Would have been nice if the README mentioned it :/

[hadess]

Filed https://github.com/ximion/appstream/issues/502 against appstream until I get the time to reimplement this once more.

[hadess]

Would have been nice if the README mentioned it :/

Done in https://github.com/hughsie/appstream-glib/pull/469