Fix Arch Linux CI

It  was missing wayland-protocol and so not installing gtk3.

util/ci/actions/archlinux-test/Dockerfile

@@ -1,5 +1,5 @@
 from archlinux/base
-run pacman -Syu --quiet --noconfirm gcc cmake make boost python2 pkg-config gettext guile git ninja gtest gmock sqlite3 webkit2gtk swig gwenhywfar aqbanking intltool libxslt postgresql-libs libmariadbclient libdbi libdbi-drivers > /dev/null
+run pacman -Syu --quiet --noconfirm gcc cmake make boost python2 pkg-config gettext gtk3 guile git ninja gtest gmock sqlite3 webkit2gtk swig gwenhywfar aqbanking intltool libxslt postgresql-libs libmariadbclient libdbi libdbi-drivers wayland-protocols > /dev/null
 run echo en_US.UTF-8 UTF-8 >> /etc/locale.gen
 run echo en_GB.UTF-8 UTF-8 >> /etc/locale.gen
 run echo fr_FR.UTF-8 UTF-8 >> /etc/locale.gen