Merge pull request #8 from ByteHamster/ci

Migrate GitLab CI to GitHub CI

Author: ByteHamster

.github/workflows/build.yml

@@ -0,0 +1,21 @@
+name: Build
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up JDK 1.8
+        uses: actions/setup-java@v1
+        with:
+          java-version: 1.8
+      - name: Setup Android SDK
+        uses: android-actions/setup-android@v2
+      - name: Check duplicated level IDs
+        run: cat app/src/main/assets/*.xml | grep "<level " | cut -d '"' -f 2 | sort -g | uniq --repeated | wc -l | xargs test 0 -eq
+      - name: Make gradle wrapper executable
+        run: chmod +x ./gradlew
+      - name: Build app
+        run: ./gradlew assembleDebug