[PRQ#45049] Deletion Request for python-umsgpack

MarsSeed [1] filed a deletion request for python-umsgpack [2]: Deprecated Python library from 2015. The AUR package never worked. But it is not actually needed by its two dependents. Safe to delete this broken package. I've left a comment on python- rpcudp page, and submitted the orphan and broken python-meshcat-git for deletion (PRQ#45048). [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/python-umsgpack/