try out github actions over travis

.github/workflows/ci.yml

@@ -0,0 +1,26 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - github-actions
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: actions/setup-java@v2
+        with:
+          java-version: 8
+          cache: maven
+
+      # https://docs.travis-ci.com/user/languages/java/#maven-dependency-management
+      - run: mvn install -DskipTests=true -Dmaven.javadoc.skip=true -B -V
+
+      # https://docs.travis-ci.com/user/languages/java/#maven-default-script-command
+      - run: mvn test -B