Update maven.yml

.github/workflows/maven.yml

+name: Java CI
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@master
+    - name: Set up JDK 1.8
+      uses: actions/setup-java@v1
+      with:
+        version: 1.8
+    - name: Build with Maven
+      run: mvn clean package -Dmaven.test.skip --file pom.xml