[gnome-builder] build: use llvm12 from flathub

[Christian Hergert <chergert src gnome org>]

commit b05caf14429d3337723d252730ba8bc0c0263a97
Author: Christian Hergert <chergert redhat com>
Date:   Fri Sep 3 10:34:09 2021 -0700

    build: use llvm12 from flathub

 .gitlab-ci.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 811b38dee..318a3e710 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -13,8 +13,8 @@ flatpak:
     APP_ID: "org.gnome.Builder"
     BUNDLE: "gnome-builder-git.flatpak"
   before_script:
-    - flatpak --user remote-add --if-not-exists flathub-beta 
https://flathub.org/beta-repo/flathub-beta.flatpakrepo
-    - flatpak --user install -y flathub-beta org.freedesktop.Sdk.Extension.llvm12//21.08beta
+    - flatpak --user remote --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
+    - flatpak --user install -y flathub org.freedesktop.Sdk.Extension.llvm12//21.08
 
 nightly:
     extends: '.publish_nightly'