Fixed GitHub Actions syntax

.github/workflows/main.yml

@@ -3,13 +3,16 @@ name: CI
 on: [push, pull_request]
 
 jobs:
-  build:
+  tests:
-    - uses: actions/checkout@v1
+    name: "Tests"
-    - name: Use Node.js 8
+    runs-on: ubuntu-latest
-      uses: actions/setup-node@v1
+    steps:
-      with:
+      - uses: actions/checkout@v1
-        node-version: 8
+      - name: Use Node.js 8
-    - name: "npm install"
+        uses: actions/setup-node@v1
-      run: npm install
+        with:
-    - name: "Run Grunt"
+          node-version: 8
-      run: grunt
+      - name: "npm install"
+        run: npm install
+      - name: "Run Grunt"
+        run: grunt