Multiterm would appear to be GTK2 only
https://github.com/geany/geany-plugins/blob/a8fd23125049d0a0ae8655e2bf95d3f4... so should not be being CIed.
Yes, but even if it is disabled (by `./configure` itself and with `--disable-plugin-multiterm` explicitly), `make distcheck` wants to call `valac` anyway.
I guess this is some autotools magic which I do not understand.
We probably should finally remove old, unmaintained plugins from G-P.