feat(*): Github Actions for PR builds (#583)

.github/workflows/pr.yml

@@ -0,0 +1,23 @@
+name: PR
+
+on: [pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - uses: actions/setup-java@v1
+      with:
+        java-version: 8
+    - uses: actions/cache@v1
+      with:
+        path: ~/.gradle
+        key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle') }}
+        restore-keys: |
+          ${{ runner.os }}-gradle-
+    - name: Build
+      env:
+        GRADLE_OPTS: -Xmx6g -Xms6g -Dorg.gradle.daemon=false
+      run: ./gradlew build