Bump django-mdeditor from 0.1.18 to 0.1.20

Bumps [django-mdeditor](https://github.com/pylixm/django-mdeditor) from 0.1.18 to 0.1.20.
- [Release notes](https://github.com/pylixm/django-mdeditor/releases)
- [Commits](pylixm/django-mdeditor@v0.1.18...v0.1.20)

---
updated-dependencies:
- dependency-name: django-mdeditor
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>