Move away from Travis to Github actions

.github/workflows/build.yml

@@ -0,0 +1,41 @@
+name: "Build"
+on:
+  push:
+    branches: [ '*' ]
+    tags-ignore:
+      - '*'
+
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+        java: [11, 15]
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up JDK ${{ matrix.java }}
+        uses: actions/setup-java@v1
+        with:
+          java-version: ${{ matrix.java }}
+          architecture: x64
+      - name: Cache Maven packages
+        uses: actions/cache@v2
+        with:
+          path: ~/.m2
+          key: ${{ runner.os }}-m2-${{ hashFiles('**/pom.xml') }}
+          restore-keys: ${{ runner.os }}-m2
+      - name: Build with Maven
+        run: mvn clean install
+
+  notify-slack:
+    if: github.event_name == 'push' && (success() || failure())
+    needs:
+      - build
+    runs-on: ubuntu-latest
+    steps:
+      - name: "Slack workflow notification"
+        uses: Gamesight/slack-workflow-status@master
+        with:
+          repo_token: ${{secrets.GITHUB_TOKEN}}
+          slack_webhook_url: ${{secrets.SLACK_WEBHOOK_URL}}