Run test only on Node v12+

.github/workflows/nodejs.yml

@@ -40,9 +40,33 @@ jobs:
       run: |
         npm run test:types
 
-    - name: DSL
+  dsl:
+    name: DSL
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      matrix:
+        node-version: [12.x, 14.x]
+        os: [ubuntu-latest, windows-latest, macOS-latest]
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v1
+      with:
+        node-version: ${{ matrix.node-version }}
+
+    - name: Install
+      run: |
+        npm install
+
+    - name: Build
       run: |
         npm run build:ts
+
+    - name: Test
+      run: |
         npm run test:dsl
 
   test-node-v8: