Compile full cross-build in CI

Author: olafurpg

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - uses: olafurpg/setup-scala@v13
-      - run: sbt test
+      - run: sbt +test
   check:
     runs-on: ubuntu-latest
     steps: