Add GitHub workflow

Author: MrPowers

.github/workflows/ci.yml

@@ -0,0 +1,16 @@
+name: CI
+on: [push, pull_request]
+
+jobs:
+  build:
+    strategy:
+      fail-fast: false
+      matrix:
+        scala: ["2.12.12"]
+        spark: ["3.0.1"]
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - uses: olafurpg/setup-scala@v10
+      - name: Test
+        run: sbt -Dspark.testVersion=${{ matrix.spark  }} ++${{ matrix.scala }} test