Bump markdownlint-cli from 0.23.2 to 0.33.0

This updates the GitHub Actions workflow to use the latest version.

.github/workflows/main.yml

@@ -39,6 +39,6 @@ jobs:
           source activate test
           pip install bandit black isort flake8
           pip install .
-          npm install -g markdownlint-cli@0.23.2
+          npm install -g markdownlint-cli@0.33.0
           make test
           scraper -h