Update nodejs

Update nodejs to 14 version

.github/workflows/check.yml

@@ -5,10 +5,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - name: Use Node.js 12
+      - name: Use Node.js 14
         uses: actions/setup-node@v1
         with:
-            node-version: 12
+            node-version: 14
       - name: run markdownlint linter
         run: |
           npm install -g markdownlint-cli