Create maven.yml (#1663)

Switch unit testing CI from Travis to GitHub actions.

.github/workflows/maven.yml

@@ -0,0 +1,26 @@
+# This workflow will build a Java project with Maven, and cache/restore any dependencies to improve the workflow execution time
+# For more information see: https://help.github.com/actions/language-and-framework-guides/building-and-testing-java-with-maven
+
+name: Java CI with Maven
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up JDK 11
+      uses: actions/setup-java@v2
+      with:
+        java-version: '11'
+        distribution: 'adopt'
+        cache: maven
+    - name: Build with Maven
+      run: mvn -B package --file pom.xml

README.md

@@ -1,6 +1,6 @@
 Anserini
 ========
-[![Build Status](https://travis-ci.org/castorini/anserini.svg?branch=master)](https://travis-ci.org/castorini/anserini)
+![build](https://github.com/castorini/anserini/actions/workflows/maven.yml/badge.svg)
 [![codecov](https://codecov.io/gh/castorini/anserini/branch/master/graph/badge.svg)](https://codecov.io/gh/castorini/anserini)
 [![Generic badge](https://img.shields.io/badge/Lucene-v8.3.0-brightgreen.svg)](https://archive.apache.org/dist/lucene/java/8.3.0/)
 [![Maven Central](https://img.shields.io/maven-central/v/io.anserini/anserini?color=brightgreen)](https://search.maven.org/search?q=a:anserini)