[gtksourceview/wip/chergert/stable-fedora] .gitlab-ci.yml: use f34

[Christian Hergert <chergert src gnome org>]

commit 6908d7bd26fc0d24484c321ebcce36e483429edc
Author: Christian Hergert <chergert redhat com>
Date:   Mon Jul 26 17:04:43 2021 -0700

    .gitlab-ci.yml: use f34

 .gitlab-ci.yml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index d1cbc0cb..9206e1d0 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -10,6 +10,7 @@ stages:
 variables:
     FEDORA_DEPS:
         meson vala gtk4-devel ninja-build pkgconf clang gobject-introspection-devel gtk-doc vulkan-headers 
docbook-style-xsl docbook-dtds
+    FEDORA_IMAGE: "registry.gitlab.gnome.org/gnome/gtk/fedora:v34"
 
 flatpak:
     image: 'registry.gitlab.gnome.org/gnome/gnome-runtime-images/gnome:master'
@@ -22,7 +23,7 @@ flatpak:
     extends: ".flatpak"
 
 reference:
-    image: fedora:rawhide
+    image: $FEDORA_IMAGE
     stage: docs
     needs: []
     variables: