[#356] Fix workflow for auto-deleted branches

Fix workflow when branches are auto-deleted after merge (i.e. configuration of github)

.github/workflows/npm-publish-beta.yml

@@ -15,8 +15,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
-          ref: ${{ github.event.pull_request.head.ref }}
-          repository: ${{ github.event.pull_request.head.repo.full_name }}
+          ref: ${{ github.event.pull_request.merge_commit_sha }}
 
       - name: Get short SHA
         id: set_sha
@@ -37,6 +36,7 @@ jobs:
         with:
           node-version: 20
           registry-url: https://registry.npmjs.org
+
       - run: npm ci
       - run: npm test
       - run: npm run build