Update main.yml

.github/workflows/main.yml

@@ -5,7 +5,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
-    - uses: actions/setup-node
+    - uses: actions/setup-node@v2
+      with:
+        node-version: '12'
     - name: Install modules
       run: yarn
     - name: Lint