Add github action to build and upload artifacts

.github/workflows/main.yaml

@@ -0,0 +1,29 @@
+name: Java CI
+
+on: [push]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up JDK 11.0.10
+        uses: actions/setup-java@v1
+        with:
+          java-version: '11.0.10'
+
+      - name: Build with Gradle
+        run: gradle build
+
+      - name: Create release
+        uses: ncipollo/release-action@v1
+        with:
+          name: latest-ci-build
+          tag: latest-ci-build
+          artifacts: "./dist/gpkg2dxf.zip"
+          allowUpdates: true
+          replacesArtifacts: true
+          artifactContentType: "application/zip"
+          token: ${{ secrets.GITHUB_TOKEN }}