Add build GitHub workflow

Part of #5

.github/workflows/build.yml

@@ -0,0 +1,39 @@
+name: Build
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
+      - uses: actions/checkout@v2
+
+      - name: Set up JDK 11
+        uses: actions/setup-java@v2
+        with:
+          java-version: '11'
+          distribution: 'adopt'
+          architecture: x64
+
+      - name: Maven Build
+        run: mvn verify
+
+      # Then upload the artifacts to the workflow
+      - name: Upload Linux artifact
+        uses: actions/upload-artifact@v2
+        with:
+          name: GEM-linux
+          path: products\org.aposin.gem.product\target\products\GEM-*.linux.*.zip
+            # Then upload the artifact to the workflow
+
+      - name: Upload Windows artifact
+        uses: actions/upload-artifact@v2
+        with:
+          name: GEM-win
+          path: products\org.aposin.gem.product\target\products\GEM-*.win32.*.zip