add JDK setup & add scala.properties.json

ci/properties/scala.properties.json

@@ -0,0 +1,6 @@
+{
+    "name": "Scala",
+    "description": "Build and test a Scala project with SBT.",
+    "iconName": "scala",
+    "categories": ["Scala", "Java"]
+}

ci/scala.yml

@@ -9,7 +9,9 @@ jobs:
     
     steps:
     - uses: actions/checkout@v1
-    - name: Compile
-      run: sbt compile
+    - name: Set up JDK 1.8
+      uses: actions/setup-java@v1
+      with:
+        java-version: 1.8
     - name: Run tests
       run: sbt test