Fix CI

.gitlab-ci.yml

-# SPDX-FileCopyrightText: 2018 Bruce Cowan <bruce@bcowan.me.uk>
+# SPDX-FileCopyrightText: 2018, 2020 Bruce Cowan <bruce@bcowan.me.uk>
 # SPDX-License-Identifier: CC0-1.0
-
-stages:
-  - build
-
 flatpak:
-  image: flatpak/flatpak-builder:gnome-3-28
+  image: fedora:latest
   stage: build
   variables:
     MANIFEST_PATH: "build-aux/uk.me.bcowan.Rugby.json"
-    RUNTIME_REPO: "https://sdk.gnome.org/gnome.flatpakrepo"
+    RUNTIME_REPO: "https://flathub.org/repo/flathub.flatpakrepo"
     FLATPAK_MODULE: "rugby"
     BUNDLE: "rugby.flatpak"
     MESON_ARGS: ""
     DBUS_ID: "uk.me.bcowan.Rugby"
 
   script:
+  - dnf install -y flatpak-builder
+  - flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
+  - flatpak install -y flathub org.gnome.Platform 3.34
+  - flatpak install -y flathub org.gnome.Sdk 3.34
   - flatpak-builder --stop-at=${FLATPAK_MODULE} app ${MANIFEST_PATH}
   - flatpak build app meson --prefix=/app ${MESON_ARGS} _build
   - flatpak build app ninja -C _build install