This adds `libgit` enabled arm builds, meaning we'll ship both with and
without libgit for arm releases. The ever growing justfile is reminding
me of the horrors often seen in Makefiles... but fixing that is left as
an exercise to the reader (likely me when I find the spoons).
This will probably be adjusted slightly on release day, experience shows
that the gh-release recipe resists improvements, but I'll deal with that
on <commit date> + ~thursday.
Closes: #1138#1060
Signed-off-by: Christina Sørensen <ces@fem.gg>
