tests require installed gsettings schemas
This is a regression from the meson port.
The output from the failed tests:
1/2 gcm-self-test FAIL
--- command ---
/tmp/tmpjc/plugins/color/gcm-self-test
--- stdout ---
/color/edid: OK
/color/sunset-sunrise: OK
/color fractional-day: OK
/color/night-light:
--- stderr ---
(gdm-self-test): GLig-GIO-ERROR:
Settings schema 'org.gnome.settings-daemon.plugins.color' is not installed