irc/smuxi: Updates to 1.2.1

Changes since 1.1:

• Dropped Glade# build dependency. The deprecated Glade library is no longer used. GTK+ and GTK # are still needed.
• Replaced Freenode with Libera.Chat
• Several crash fixes, one that crashes the UI when you save a new server
• New translations: Georgian, Basque, Croatian
• Bump minimum Mono version to 5.18
• Dropped Transifex as a translation source. All translation updates are now coming only from the GNOME project for consistency/quality.

PR: 274923
Reported by: Chris Petrik <Christopher.petrik@usm.edu>