chore: introduce GitHub actions (#4)

Author: CarstenWickner

.github/workflows/maven.yml

@@ -0,0 +1,42 @@
+name: Java CI (Maven)
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+  release:
+    types:
+      - created
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        java-version: ['1.8', '11']
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up JDK ${{ matrix.java-version }}
+      uses: actions/setup-java@v1
+      with:
+        java-version: ${{ matrix.java-version }}
+    - name: Build
+      run: mvn install -DskipTests=true -Dcheckstyle.skip=true -Dmaven.javadoc.skip=true -Dgpg.skip=true -B -V
+      env:
+        CI: true
+    - name: Test
+      run: mvn test -B
+      env:
+        CI: true
+    - name: Checkstyle
+      run: mvn verify -DskipTests=true -Dmaven.javadoc.skip=true -Dgpg.skip=true -B
+      env:
+        CI: true
+    - name: Generate JavaDoc
+      run: mvn javadoc:javadoc -B
+      env:
+        CI: true

.travis.yml

@@ -1,5 +1,5 @@
 # Java JSON Schema Generator – Module javax.validation
-[![Build Status](https://travis-ci.org/victools/jsonschema-module-javax-validation.svg?branch=master)](https://travis-ci.org/victools/jsonschema-module-javax-validation)
+[![Build Status](https://github.com/victools/jsonschema-module-javax-validation/workflows/Java%20CI%20(Maven)/badge.svg)](https://github.com/victools/jsonschema-module-javax-validation/actions?query=workflow%3A%22Java+CI+%28Maven%29%22)
 [![Maven Central](https://maven-badges.herokuapp.com/maven-central/com.github.victools/jsonschema-module-javax-validation/badge.svg)](https://maven-badges.herokuapp.com/maven-central/com.github.victools/jsonschema-module-javax-validation)
 
 Module for the `jsonschema-generator` – deriving JSON Schema attributes from `javax.validation.constraints` annotations.