Remove the folder on build server once PR is merged

.github/workflows/cleanup_pr.yml

@@ -0,0 +1,24 @@
+name: Cleanup after PR
+
+on:
+  pull_request:
+    types: [closed]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Extract branch name
+      shell: bash
+      run: echo "##[set-output name=branch;](echo{GITHUB_REF#refs/heads/})"
+      id: extract_branch
+    - name: Delete folder on builds.jabref.org
+      uses: appleboy/[email protected]
+      with:
+        script: rm -rf www/${{ steps.extract_branch.outputs.branch }}
+        host: builds.jabref.org
+        username: builds_jabref_org
+        privateKey: ${{ secrets.buildJabRefPrivateKey }}
+        port: 9922