Add pre-release CI config (#1)

.github/workflows/pre-release.yml

@@ -0,0 +1,24 @@
+name: Pre-release check
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: kssm
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up JDK 1.8
+      uses: actions/setup-java@v1
+      with:
+        java-version: 1.8
+    - name: Grant execute permission for gradlew
+      run: chmod +x ./gradlew
+    - name: Build and check with Gradle
+      run: ./gradlew build