- Update puppet-concat (v7.3.1 instead of v7.1.1)
- Update puppet-stdlib (v8.5.0 instead of v8.1.0)

This reverts commit fc3fc915.

- Validate Vagrantfile
- Shell scripts linter
- Yaml files linter
- JSON files linter
- Markdown files linter
- Check that Markdown links and images reference existing local files and headings.
- Check that external URLs in Markdown files are alive.