Add release-to-bintray workflow

.github/workflows/release-to-bintray.yml

@@ -0,0 +1,16 @@
+name: Release to Bintray
+on:
+  push:
+    tags:
+      - v[0-9].[0-9]+.[0-9]+
+      - v[0-9].[0-9]+.[0-9]+-rc.[0-9]+
+jobs:
+  build:
+    runs-on: ubuntu-18.04
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-java@v1
+        with:
+          java-version: 8
+      - name: Build and release to Bintray
+        run: ./gradlew -Prelease.useLastTag=true candidate publishNebulaPublicationToBintrayRepository --info