CI: Use 3.28 image until master is fixed

And run only headless tests, as things are a bit on flow now and the
ostree image is missing some needed bits.

.gitlab-ci.yml

@@ -14,11 +14,11 @@ stages:
       - ninja test
 
 flatpak:
-    image: registry.gitlab.gnome.org/gnome/gnome-nightly-oci/nightly:master
+    image: registry.gitlab.com/alatiera/flatpak-docker-images/gnome:3.28
     stage: test
     variables:
         MANIFEST_PATH: "build-aux/flatpak/org.gnome.Nautilus.json"
-        MESON_ARGS: "-Dprofile=development -Dtests=all"
+        MESON_ARGS: "-Dprofile=development -Dtests=headless"
         FLATPAK_MODULE: "nautilus"
         RUNTIME_REPO: "https://sdk.gnome.org/gnome-nightly.flatpakrepo"
         DBUS_ID: "org.gnome.NautilusDevel"
@@ -33,7 +33,7 @@ flatpak:
         # Generate a Flatpak bundle
         - flatpak build-bundle repo ${BUNDLE} --runtime-repo=${RUNTIME_REPO} ${DBUS_ID}
         # Run automatic tests inside the Flatpak env
-        - xvfb-run -a -s "-screen 0 1024x768x24" flatpak build app ninja -C _build test
+        - flatpak build app ninja -C _build test
     artifacts:
         paths:
             - ${BUNDLE}

build-aux/flatpak/org.gnome.Nautilus.json

@@ -20,7 +20,16 @@
         {
             "name": "meson",
             "buildsystem": "simple",
-            "build-commands": ["pip3 install meson"]
+             "build-commands": [
+                "python3 setup.py install --prefix=/app"
+            ],
+            "sources": [
+                {
+                    "type": "archive",
+                    "url": "https://github.com/mesonbuild/meson/archive/0.46.1.tar.gz",
+                    "sha256": "2d917692d2cc194e12295f00469fbdf3c045e85d0295e5e59ced69115920ffa0"
+                }
+            ]
         },
         {
             "name": "exiv2",