Release 0.0.21

Diff

0.0.20...266c6ec0

Checklist

• Update the versions according to SemVer
  • lib/glfm_markdown/version.rb
  • ext/glfm_markdown/Cargo.toml
• Update "Currently using..." in README.md if version of comrak was updated
• Ensure that Cargo.lock is updated by doing rake clobber; rake compile
• Ensure diff link above is up-to-date
• Check the release notes: https://gitlab.com/api/v4/projects/gitlab-org%2Fruby%2Fgems%2Fgitlab-glfm-markdown/repository/changelog?version=0.0.21

Once merged, the fact that lib/glfm_markdown/version.rb was updated will cause CI to publish a new version to RubyGems.