systemd/plasma-workspace: upgrade to 6.1.2
I'm pretty sure there's a lot of other outdated forked packages in the staging repo, but this one was causing an apk upgrade failure:
ERROR: plasma5support-6.1.2-r1: trying to overwrite usr/lib/qt6/plugins/plasma5support/dataengine/plasma_engine_devicenotifications.so owned by plasma-workspace-9999_git20240428-r0.
ERROR: plasma5support-6.1.2-r1: trying to overwrite usr/lib/qt6/plugins/plasma5support/dataengine/plasma_engine_keystate.so owned by plasma-workspace-9999_git20240428-r0.
ERROR: plasma5support-6.1.2-r1: trying to overwrite usr/share/plasma5support/services/modifierkeystate.operations owned by plasma-workspace-9999_git20240428-r0.