Update metainfo.xml on release
See https://source.puri.sm/Librem5/calls/-/blob/master/data/sm.puri.Calls.metainfo.xml#L67 and the spec: https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html#tag-releases
I'm wondering if I could come up with something similar to https://source.puri.sm/Librem5/calls/-/blob/master/debian/gbp.conf#L10 to make my life easier.