ci: fix check-git-branches regex

.github/workflows/check-git-branches.yml

@@ -17,7 +17,7 @@ jobs:
           fetch-depth: 0
       - name: Set output variable to latest release branch
         id: step2
-        run: echo "latest_release=$(git branch -r | grep -E 'release/v[0-9]+\.[0-9]+\.[0-9]+' | tail -n 1 | sed 's/  origin\///')" >> $GITHUB_OUTPUT
+        run: echo "latest_release=$(git branch -r | grep -E 'release/v[0-9]+\.[0-9]+\.[0-9]+$' | sort -V | tail -n 1)" >> $GITHUB_OUTPUT
   check-merge-master:
     name: Check that the release branch merges into master
     needs: get_release
@@ -29,6 +29,6 @@ jobs:
           fetch-depth: 0
       - name: Check merge master
         run: |
-          ./.github/workflows/support-files/git-merge-check.sh master $branch1
+          ./.github/workflows/support-files/git-merge-check.sh origin/master $branch1
         env:
           branch1: ${{needs.get_release.outputs.output1}}