[gnome-music/wip/jfelder/3-34-unprivileged-ci] CI: Update to run as unprivileged

[Jean Felder <jfelder src gnome org>]

commit 2d7c72b3227b34fe34df94e54b1338a50b4e0b69
Author: Jean Felder <jfelder src gnome org>
Date:   Fri Feb 21 11:55:30 2020 +0100

    CI: Update to run as unprivileged
    
    There is no default image for the runner. An image needs to be
    specified in order to install flake8.

 .gitlab-ci.yml | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 88b15236..3e9a16f9 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,4 +1,5 @@
 image: registry.gitlab.gnome.org/gnome/gnome-runtime-images/gnome:3.34
+image: fedora:28
 stages:
   - check
   - build-flatpak