Switch back to debian testing

unstable breaks too much to be useful for CI. To keep CI green, we
stop installing pacman-package-manager in the default images and disable
debian tools tree in CI.

.github/workflows/ci.yml

@@ -120,6 +120,9 @@ jobs:
           # TODO: Try again once Arch gets a new rpm release.
           - distro: centos
             tools: arch
+          # TODO: Re-enable once pacman-package-manager is back in testing
+          - distro: arch
+            tools: debian
 
     steps:
     - uses: actions/checkout@9bb56186c3b09b4f86b1c65136769dd318469633
@@ -181,7 +184,5 @@ jobs:
             --verbose \
             -m integration \
             --distribution ${{ matrix.distro }} \
-            $([ "${{ matrix.distro }}" = "debian" ] && echo --release=unstable) \
-            $([ "${{ matrix.tools }}" = "debian" ] && echo --tools-tree-release=unstable) \
             --tools-tree-distribution ${{ matrix.tools }} \
             tests/

mkosi.conf.d/20-debian/mkosi.conf

@@ -4,7 +4,7 @@
 Distribution=debian
 
 [Distribution]
-@Release=unstable
+@Release=testing
 Repositories=non-free-firmware
 
 [Content]

mkosi.conf.d/30-debian-ubuntu/mkosi.conf.d/20-not-focal.conf

@@ -9,6 +9,7 @@ Packages=
         archlinux-keyring
         dbus-broker
         dnf
-        makepkg
-        pacman-package-manager
+        # TODO: Make required again once pacman-package-manager is back in testing.
+        ?exact-name(makepkg)
+        ?exact-name(pacman-package-manager)
         swtpm

mkosi/resources/mkosi-tools/mkosi.conf.d/10-debian-ubuntu.conf

@@ -21,7 +21,8 @@ Packages=
         makepkg
         openssh-client
         ovmf
-        pacman-package-manager
+        # TODO: Make required again once pacman-package-manager is back in testing.
+        ?exact-name(pacman-package-manager)
         pesign
         policycoreutils
         python3-cryptography