Add workflow to auto update releaser workflows (#20)

.github/workflows/update-workflows.yml

@@ -0,0 +1,53 @@
+name: Update releaser worflows
+
+on:
+  pull_request_target:
+  schedule:
+    - cron: '0 2 20 * *'
+
+jobs:
+  releaser_workflows:
+    name: Update releaser workflows
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: write
+      pull-requests: write
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - run: |
+          set -eux
+          wget https://github.com/jupyter-server/jupyter_releaser/blob/main/example-workflows/prep-release.yml
+          wget https://github.com/jupyter-server/jupyter_releaser/blob/main/example-workflows/publish-release.yml
+        working-directory: template/.github/workflows
+
+      - name: List files changed
+        id: files-changed
+        shell: bash -l {0}
+        run: |
+          set -ex
+          export CHANGES=$(git status --porcelain | tee /tmp/modified.log | wc -l)
+          cat /tmp/modified.log
+
+          echo "N_CHANGES=${CHANGES}" >> $GITHUB_OUTPUT
+
+          git diff
+
+      - name: Commit any changes
+        if: steps.files-changed.outputs.N_CHANGES != '0'
+        shell: bash -l {0}
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+
+          git pull --no-tags
+
+          git add *
+          git commit -m "Automatic update of the releaser workflows"
+
+          git config push.default upstream
+          git push
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}