Setup GitHub Actions for CI (#19)

Author: takezoe

.github/workflows/build.yml

@@ -0,0 +1,35 @@
+name: build
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Cache
+      uses: actions/cache@v2
+      env:
+        cache-name: cache-sbt-libs
+      with:
+        path: |
+          ~/.ivy2/cache
+          ~/.sbt
+          ~/.coursier
+        key: build-${{ env.cache-name }}-${{ hashFiles('build.sbt') }}
+    - name: Set up JDK
+      uses: actions/setup-java@v2
+      with:
+        java-version: '8'
+        distribution: 'adopt'
+    - name: Run tests
+      run: sbt test
+    - name: Assembly
+      run: |
+        npm install
+        npm run-script release
+    - name: Upload artifacts
+      uses: actions/upload-artifact@v2
+      with:
+        name: gitbucket-explorer-plugin-${{ github.sha }}
+        path: ./target/scala-2.13/*.jar