Adapt our archlinux docker config to changes in the upstream DockerHub container definition

* archlinux renamed its container from base/archlinux to archlinux/base
* gettext is no longer installed by default

util/ci/arch-docker

@@ -1,5 +1,5 @@
-from base/archlinux
+from archlinux/base
-run pacman -Syu --quiet --noconfirm gcc cmake make boost python2 pkg-config 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 guile git ninja gtest gmock sqlite3 webkit2gtk swig gwenhywfar aqbanking intltool libxslt postgresql-libs libmariadbclient libdbi libdbi-drivers > /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