ci: directly use archlinux:multilib-devel

I've introduced the container an year or so ago, to avoid the manual
pacman.conf fiddle. Although the last few months it wasn't quite working
as expected due to expired publishing tokens et al.

With that fixed we can use it \o/

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>

.github/actions/setup-archlinux/action.yml

@@ -11,23 +11,15 @@ runs:
     - name: Install dependencies
       shell: bash
       run: |
-        # Enable multilib, for building 32bit binaries
-        echo -e '[multilib]\nInclude = /etc/pacman.d/mirrorlist' >> /etc/pacman.conf
-        # Semi-regularly the packager key may have (temporarily) expired.
-        # Somewhat robust solution is to wipe the local keyring and
-        # regenerate/reinstall it prior to any other packages on the system.
-        rm -rf /etc/pacman.d/gnupg
         pacman-key --init
         pacman-key --populate
         pacman --noconfirm -Sy archlinux-keyring
 
         pacman --noconfirm -Su \
-          base-devel \
           git \
           lib32-libusb \
           lib32-systemd \
           libusb \
           linux-headers \
-          multilib-devel \
           meson \
           systemd

.github/workflows/main.yml

@@ -24,7 +24,7 @@ jobs:
       matrix:
         include:
           - container: 'alpine:latest'
-          - container: 'archlinux:base-devel'
+          - container: 'archlinux:multilib-devel'
             crossfile: 'arch-cross.ini'
           - container: 'debian:unstable'
             crossfile: 'debian-cross.ini'