build(deps): bump myst-parser from 0.17.2 to 0.18.0 (#541)

Bumps [myst-parser](https://github.com/executablebooks/MyST-Parser) from 0.17.2 to 0.18.0.
- [Release notes](https://github.com/executablebooks/MyST-Parser/releases)
- [Changelog](https://github.com/executablebooks/MyST-Parser/blob/master/CHANGELOG.md)
- [Commits](executablebooks/MyST-Parser@v0.17.2...v0.18.0)

---
updated-dependencies:
- dependency-name: myst-parser
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

docs/requirements.txt

@@ -1,2 +1,2 @@
-myst-parser==0.17.2
+myst-parser==0.18.0
 sphinx_rtd_theme==1.0.0