update github builder to run on windows and linux

.github/workflows/maven.yml

@@ -5,7 +5,11 @@ on: [ push, pull_request ]
 jobs:
   build:
 
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      matrix:
+        os: [ ubuntu-latest, windows-latest ]
 
     steps:
     - uses: actions/checkout@v2