[gnome-runtime-images] Revert "CI: use `latest` tag for the fedora images"

[Jordan Petridis <jpetridis src gnome org>]

commit 3b84c7a092c7c5684737545adb643f4bd6115cb6
Author: Jordan Petridis <jpetridis gnome org>
Date:   Thu Jul 15 09:38:26 2021 +0000

    Revert "CI: use `latest` tag for the fedora images"
    
    This reverts commit ff51db2d655f8fad96d737230a8083d7e50ae4a6

 .gitlab-ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 5f0ecae..80d6e97 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,4 +1,4 @@
-image: 'registry.fedoraproject.org/fedora:latest'
+image: 'registry.fedoraproject.org/fedora:32'
 
 # Buildah can't use 'overlay' driver when running inside docker
 variables: