adding deploy action for release branches

Author: Matt

.github/workflows/github-action-deploy.yml

@@ -0,0 +1,23 @@
+name: Publish to GitHub Packages on Release Branch
+
+on:
+  workflow_run:
+    workflow: "Java Leaflet Build"
+    type: completed
+    branches:
+      - 'releases/**'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: actions/setup-java@v1
+        with:
+          java-version: 1.8
+
+      - name: Deploy to GitHub Packages
+        env:
+          GITHUB_TOKEN: ${{ secrets.DEPLOY_PACKAGE_TOKEN }}
+        run: mvn deploy