use specific markdown link check version

.github/workflows/markdown-ci.yml

@@ -27,5 +27,5 @@ jobs:
     steps:
     - uses: actions/checkout@v2
     - run: |
-        npm install markdown-link-check
+        npm install markdown-link-check@3.11.2
         find . -type d \( -name node_modules -o -name .github \) -prune -o -type f -name '*.md' -print0 | xargs -0 -n1 node_modules/.bin/markdown-link-check --config ./tools/.markdownlinkcheck.json --quiet