ci: add sync-release-as workflow to mirror release PR title version

Stainless-Generated-From: 6653323935ddca06979e5427c9165c5e67377d5f

Author: manu4543

.github/workflows/sync-release-as.yml

@@ -0,0 +1,63 @@
+name: Sync Release-As from release PR title
+
+on:
+  pull_request:
+    types: [edited]
+
+permissions:
+  contents: write
+
+jobs:
+  sync:
+    if: >-
+      github.event.pull_request.base.ref == 'master' &&
+      startsWith(github.event.pull_request.head.ref, 'release-please--') &&
+      github.event.changes.title != null
+    runs-on: ubuntu-latest
+    steps:
+      - name: Extract versions from old and new title
+        id: parse
+        env:
+          NEW_TITLE: ${{ github.event.pull_request.title }}
+          OLD_TITLE: ${{ github.event.changes.title.from }}
+        run: |
+          # Anchored on pull-request-title-pattern "release: ${version}" from release-please-config.json.
+          extract() {
+            echo "$1" | grep -oE '^release:[[:space:]]+v?[0-9]+\.[0-9]+\.[0-9]+(-[0-9A-Za-z.-]+)?' \
+              | sed -E 's/^release:[[:space:]]+v?//'
+          }
+          NEW_VERSION=$(extract "$NEW_TITLE")
+          OLD_VERSION=$(extract "$OLD_TITLE")
+          echo "old=$OLD_VERSION"
+          echo "new=$NEW_VERSION"
+          if [ -z "$NEW_VERSION" ]; then
+            echo "::notice::No semver in new title; nothing to do."
+            echo "skip=true" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+          if [ "$NEW_VERSION" = "$OLD_VERSION" ]; then
+            echo "::notice::Version unchanged ($NEW_VERSION); not pushing."
+            echo "skip=true" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+          echo "version=$NEW_VERSION" >> "$GITHUB_OUTPUT"
+
+      - name: Check out master
+        if: steps.parse.outputs.skip != 'true'
+        uses: actions/checkout@v6
+        with:
+          ref: master
+          token: ${{ secrets.RELEASE_PLEASE_TOKEN }}
+          fetch-depth: 1
+
+      - name: Push empty Release-As commit
+        if: steps.parse.outputs.skip != 'true'
+        env:
+          VERSION: ${{ steps.parse.outputs.version }}
+        run: |
+          git config user.name "release-as-bot"
+          git config user.email "release-as-bot@users.noreply.github.com"
+          git commit --allow-empty -m "chore: pin next release
+
+          Release-As: ${VERSION}"
+          git push origin master