This slipped so far this cycle, let's do it in time for the alpha
release.
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2817>
# the Cogl and Clutter libraries also use this API version.
# The API version is increased each development cycle,
# starting with 0 in 3.23.x
-mutter_api_version = '12'
+mutter_api_version = '13'
clutter_pc = 'mutter-clutter-' + mutter_api_version
cogl_pc = 'mutter-cogl-' + mutter_api_version