update node.js version

Author: kyoto7250

.github/workflows/remark.yml

@@ -21,7 +21,7 @@ jobs:
     - name: Setup Node.js
       uses: actions/setup-node@v1.4.4
       with:
-        node-version: '12.x'
+        node-version: '14.x'
 
     - name: Install remark
       run: npm install remark-cli remark-lint remark-lint-maximum-line-length remark-preset-lint-recommended remark-gfm