Use GitHub Actions for run tests

.github/workflows/test.yml

@@ -0,0 +1,21 @@
+name: test
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        java: [1.8, 11, 14, 15]
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up JDK ${{ matrix.java }}
+      uses: actions/setup-java@v1
+      with:
+        java-version: ${{ matrix.java }}
+    - name: Run tests
+      run: sbt test

README.md

@@ -1,5 +1,6 @@
 # Kaitai Struct: compiler
 
+![Build Status](https://img.shields.io/github/workflow/status/kaitai-io/kaitai_struct_compiler/test)
 [![Maven Central](https://img.shields.io/maven-central/v/io.kaitai/kaitai-struct-compiler_2.12)](https://search.maven.org/artifact/io.kaitai/kaitai-struct-compiler_2.12)
 
 [![npm@latest](https://img.shields.io/npm/v/kaitai-struct-compiler/latest)](https://www.npmjs.com/package/kaitai-struct/v/latest)