ci: Build ci and nightly flatpak in release mode

Fixes: https://gitlab.gnome.org/GNOME/fractal/-/issues/979

.gitlab-ci.yml

@@ -15,7 +15,9 @@ flatpak:
     FLATPAK_MODULE: "fractal"
     APP_ID: "org.gnome.Fractal.Devel"
     RUNTIME_REPO: "https://nightly.gnome.org/gnome-nightly.flatpakrepo"
+    CONFIG_OPTS: "-Dprofile=default"
   script:
+    - rewrite-flatpak-manifest ${MANIFEST_PATH} ${FLATPAK_MODULE} ${CONFIG_OPTS}
     - >
       xvfb-run -a -s "-screen 0 1024x768x24"
       flatpak-builder --keep-build-dirs --user --disable-rofiles-fuse flatpak_app --repo=repo ${BRANCH:+--default-branch=$BRANCH} ${MANIFEST_PATH}