Add a GitHub Actions workflow

.github/workflows/ci.yml

@@ -0,0 +1,21 @@
+name: Continuous Integration
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up JDK
+        uses: actions/setup-java@v3
+        with:
+          java-version: 17
+          distribution: temurin
+          cache: sbt
+      - name: Build
+        run: sbt +publishLocal