Build against Guile 3.0

Since LilyPond 2.24.3, we (upstream) officially support Guile 3.0. While Guile 2.2 remained the recommended version for the 2.24 series, current development versions only support Guile 3.0 and there will (hopefully) be a stable release at some point (mid next year?). Since the switch in master, I am not aware of any problems (apart from issues specific to Windows compatibility) so the point of this MR is to discuss if Arch Linux would want to build LilyPond against Guile 3.0 already now. As a benefit, this would allow to drop the guile2.2 package which is only required by lilypond: https://archlinux.org/packages/extra/x86_64/guile2.2/

P.S. I'm aware of the ongoing rebuild against Python 3.13, so merging and releasing might need synchronization...