[geary/gnumdk/mainline] Update (or drop) the Docker image used by Flatpak job

[Cédric Bellegarde <cbellegarde src gnome org>]

commit 12bfcb510499ea65b1bf3f449b3bc14bf84fb9be
Author: Bartłomiej Piotrowski <b bpiotrowski pl>
Date:   Wed Jul 27 12:39:55 2022 +0200

    Update (or drop) the Docker image used by Flatpak job
    
    The gnome-runtime-images have been recently migrated to Quay. This is already reflected in the template.
    
    Please note this MR has been created semi-automatically. If it doesn't make sense, feel free to close it.

 .gitlab-ci.yml | 1 -
 1 file changed, 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 5066c3976..6f7cf8419 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -83,7 +83,6 @@ ubuntu:
     expire_in: 2 days
 
 flatpak:
-  image: 'registry.gitlab.gnome.org/gnome/gnome-runtime-images/gnome:master'
   variables:
     APP_ID: org.gnome.Geary.Devel
     FLATPAK_MODULE: geary