CI: Add workaround for dependencies removed from Debian Testing

to make it possible for CI to pass, until Squeekboard has been ported to
GTK4 or GTK4-layer-shell.

Part-of: <https://gitlab.gnome.org/World/Phosh/squeekboard/-/merge_requests/633>

.gitlab-ci.yml

@@ -23,7 +23,9 @@ stages:
   - deploy
 
 before_script:
-  - echo "deb http://deb.debian.org/debian/ experimental main" > /etc/apt/sources.list.d/experimental.list
+# Workaround for unavailable dependencies
+  - mv debian/control.debian-testing debian/control
+# End of workaround for unavailable dependencies
   - apt-get -y update
   - apt-get -y install ca-certificates
 
@@ -46,7 +48,6 @@ build_meson:
       - _build
     expire_in: 3h
   script:
-    - apt-get -y install -t experimental librust-serde-yaml-dev
     - apt-get -y build-dep .
     - meson . _build/ -Ddepdatadir=/usr/share -Dfind_orphans=true --werror
     - ninja -C _build install
@@ -63,9 +64,18 @@ build_deb:
       - '*.deb'
   script:
     - rm -f ../*.deb
-    - apt-get -y install -t experimental librust-serde-yaml-dev
     - apt-get -y build-dep .
     - apt-get -y install devscripts
+# Workaround for unavailable dependencies
+# TODO: Port Squeekboard to GTK4/GTK4-layer-shell
+# https://gitlab.gnome.org/World/Phosh/squeekboard/-/issues/64
+    - echo "deb http://deb.debian.org/debian/ unstable main" > /etc/apt/sources.list.d/unstable.list
+    - echo "deb http://deb.debian.org/debian/ experimental main" > /etc/apt/sources.list.d/experimental.list
+    - apt-get -y update
+    - apt-get -y --no-upgrade install librust-gio-dev librust-glib-dev librust-glib-sys-dev
+      librust-gtk-dev librust-gtk-sys-dev
+    - apt-get -y --no-upgrade install -t experimental librust-serde-yaml-dev
+# End of workaround for unavailable dependencies
     - REV=$(git log -1 --format=%h)
     - VER=$(dpkg-parsechangelog -SVersion)
     - DEBFULLNAME="Librem5 CI"
@@ -83,7 +93,6 @@ build_reference:
     paths:
       - _build/doc
   script:
-    - apt-get -y install -t experimental librust-serde-yaml-dev
     - apt-get -y build-dep .
     - apt-get -y install cargo
     - cd _build
@@ -98,7 +107,6 @@ test:
     - job: build_meson
       artifacts: true
   script:
-    - apt-get -y install -t experimental librust-serde-yaml-dev
     - apt-get -y build-dep .
     - apt-get -y install clang-tidy
     - ninja -C _build test
@@ -111,7 +119,6 @@ test_style:
   stage: test
   needs: []
   script:
-    - apt-get -y install -t experimental librust-serde-yaml-dev
     - apt-get -y build-dep .
     - tools/style-check_source
   except: