CI - Allow pull requests to master from any branch

Remove the workflow that only allowed pull requests to master from development, which no longer exists.

.github/workflows/pr-branch.yml

@@ -1,17 +0,0 @@
-name: Check pull request branch
-on:
-  pull_request_target:
-    types:
-      - opened
-      - reopened
-      - synchronize
-jobs:
-  check-branches:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Check branches
-        run: |
-          if [ ${{ github.head_ref }} != "development" ] && [ ${{ github.base_ref }} == "master" ]; then
-            echo "Merge requests to master are only allowed from development."
-            exit 1
-          fi