adds workflow to notify bluprint_graphics-kit to create a PR to update the library

.github/workflows/notify-downstream.yaml

@@ -0,0 +1,16 @@
+name: Notify downstream repositories
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  dispatch:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Dispatch to bluprint_graphics-kit
+        uses: peter-evans/repository-dispatch@v4
+        with:
+          token: ${{ secrets.REPO_PAT_TOKEN }}
+          repository: reuters-graphics/bluprint_graphics-kit
+          event-type: dependency-updated