community/gajim: upgrade to 2.1.0
https://dev.gajim.org/gajim/gajim/-/blob/2.1.0/ChangeLog
and switch to GitLab-source to mitiage against manipulated tarballs
https://dev.gajim.org/gajim/gajim/-/blob/2.1.0/ChangeLog
and switch to GitLab-source to mitiage against manipulated tarballs