Add job to create a GitHub release (#8248)

* Add job to create a GitHub release

* Add release notes link and header to beginning of release notes

* Add link to release notes and custom header

.github/workflows/release-prod.yml

@@ -124,3 +124,35 @@ jobs:
         curl -X POST -H "Content-Type:application/json" \
         -d "{\"version\":\"$BASE_VERSION\",\"date\":\"$DATE\"}" \
         $RELEASE_TRACKER_URL/logProduction
+    - name: Create Github release
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      run: |
+        # Get the newest release tag for the firebase package (e.g. [email protected])
+        NEWEST_TAG=$(git describe --tags --match "firebase@[0-9]*.[0-9]*.[0-9]*" --abbrev=0)
+
+        # Get the release notes from the description of the most recent merged PR into the "release" branch
+        # See: https://github.com/firebase/firebase-js-sdk/pull/8236 for an example description
+        JSON_RELEASE_NOTES=$(gh pr list \
+          --repo "$GITHUB_REPOSITORY" \
+          --state "merged" \
+          --base "release" \
+          --limit 1 \
+          --json "body" \
+          | jq '.[].body | split("\n# Releases\n")[-1]' # Remove the generated changesets header
+        )
+         
+        # Prepend the new release header
+        # We have to be careful to insert the new release header after a " character, since we're
+        # modifying the JSON string
+        JSON_RELEASE_NOTES="\"For more detailed release notes, see [Firebase JavaScript SDK Release Notes](https://firebase.google.com/support/release-notes/js).\n\n# What's Changed\n\n${JSON_RELEASE_NOTES:1}"
+
+        # Format the JSON string into a readable markdown string
+        RELEASE_NOTES=$(echo -E $JSON_RELEASE_NOTES | jq -r .)
+
+        # Create the GitHub release
+        gh release create "$NEWEST_TAG" \
+          --repo "$GITHUB_REPOSITORY" \
+          --title "$NEWEST_TAG" \
+          --notes "$RELEASE_NOTES" \
+          --verify-tag