mkosi: Re-enable arch but disable keyring checking

No need to disable arch completely, let's just disable keyring checking
to get CI working again for now.

(cherry picked from commit 16173ab)
(cherry picked from commit 93bb992)

Author: DaanDeMeyer

.github/workflows/mkosi.yml

@@ -97,6 +97,13 @@ jobs:
         KernelCommandLine=${{ env.KERNEL_CMDLINE }}
         EOF
 
+        # TODO: Remove once archlinux-keyring is updated in ppa:michel-slm/kernel-utils.
+        tee mkosi.conf.d/arch/11-arch-keyring.conf <<- EOF
+        [Distribution]
+        Distribution=arch
+        RepositoryKeyCheck=no
+        EOF
+
     - name: Generate secure boot key
       run: mkosi genkey