CI: fix markdown lint (#1389)

Author: kevmoo

.github/workflows/markdown_linter.yml

@@ -15,16 +15,6 @@ jobs:
       - uses: gaurav-nelson/github-action-markdown-link-check@v1
   markdown_lint:
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        node-version: [ 14.x ]
     steps:
       - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11
-      - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@b39b52d1213e96004bfcb1c61a8a6fa8ab84f3e8
-        with:
-          node-version: ${{ matrix.node-version }}
-      - name: Install dependencies
-        run: npm install --global markdownlint-cli2
-      - name: Run lint check
-        run: markdownlint-cli2-fix "**/*.md"
+      - uses: DavidAnson/markdownlint-cli2-action@v9