add workflow

.github/workflows/gradle.yml

@@ -0,0 +1,28 @@
+name: Publish to Maven
+
+on:
+  push:
+    branches:
+      - master
+env:
+  TOKEN: ${{ github.MVNTOKEN }}
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Set up JDK 11
+        uses: actions/setup-java@v2
+        with:
+          distribution: 'adopt'
+          java-version: '11'
+
+      - name: Grant execute permission for gradlew
+        run: chmod +x ./gradlew
+
+      - name: Build with Gradle
+        run: ./gradlew publish -Ptoken='$TOKEN'