Updated ref to use lastest code from PR; not merge

Previously, a version of the code was used that was how a merge could look like.
Now, the code is used as it is in the PR

.github/workflows/gitlab_ci.yml

@@ -68,8 +68,9 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v3
         with:
-          ref: "${{ github.event.pull_request.merge_commit_sha }}"
+          ref: "${{ github.event.pull_request.head.sha }}"
           persist-credentials: false
+          fetch-depth: 0
       - name: Mirror and wait for Gitlab-CI
         uses: jakob-fritz/github2lab_action@Iss35_mirror_pr
         env: