add regular build workflow

.github/workflows/build.yml

@@ -0,0 +1,12 @@
+name: Regular build
+on: [push]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-java@v1
+        with:
+          java-version: 1.8
+      - name: Build
+        run: ./gradlew build