Run CI also on MacOS

.github/workflows/verify.yaml

@@ -20,23 +20,12 @@ name: Linux & Windows CI
 on: [push, pull_request]
 
 jobs:
-  linux:
-    runs-on: ubuntu-18.04
-    strategy:
-      matrix:
-        java: [ 8, 11, 14 ]
-    steps:
-    - uses: actions/checkout@v1
-    - name: Set up JDK
-      uses: actions/setup-java@v1
-      with:
-        java-version: ${{ matrix.java }}
-    - name: Build with Maven
-      run: ./mvnw clean verify -B -ntp
-  windows:
-    runs-on: windows-2019
+  verify:
+    runs-on: ${{ matrix.os }}
     strategy:
+      fail-fast: false
       matrix:
+        os: [ ubuntu-18.04, macos-10.15, windows-2019 ]
         java: [ 8, 11, 14 ]
     steps:
     - uses: actions/checkout@v1