[nautilus/fixing-CI] CI: Use 3.28 image until master is fixed

[Carlos Soriano <csoriano src gnome org>]

commit f15fd69a6a244f168bbae22cc15653fcceccb9d7
Author: Carlos Soriano <csoriano1618 gmail com>
Date:   Fri May 18 06:17:24 2018 +0000

    CI: Use 3.28 image until master is fixed

 .gitlab-ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 33f06b9cb..09ea38a64 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -14,7 +14,7 @@ stages:
       - ninja test
 
 flatpak:
-    image: registry.gitlab.gnome.org/gnome/gnome-nightly-oci/nightly:master
+    image: registry.gitlab.com/alatiera/flatpak-docker-images:3.28
     stage: test
     variables:
         MANIFEST_PATH: "build-aux/flatpak/org.gnome.Nautilus.json"