Cleanup stale branches, if any

.gitlab-ci.yml

@@ -57,10 +57,11 @@ check updates:
     # Update flakes
     - nix flake update
     # Push changes
+    - git branch -D flakes_update || true
     - git checkout -b flakes_update
     - git add flake.lock
     - git commit -m 'Update NixOS Flakes'
-    - git push --set-upstream origin flakes_update -o merge_request.create
+    - git push -f --set-upstream origin flakes_update -o merge_request.create
   rules:
     - if: $CI_PIPELINE_SOURCE == "schedule"