Bump sphinxcontrib-mermaid from 0.3.1 to 0.4.0 (#317)

Bumps [sphinxcontrib-mermaid](https://github.com/mgaitan/sphinxcontrib-mermaid) from 0.3.1 to 0.4.0.
- [Release notes](https://github.com/mgaitan/sphinxcontrib-mermaid/releases)
- [Changelog](https://github.com/mgaitan/sphinxcontrib-mermaid/blob/master/CHANGELOG.rst)
- [Commits](mgaitan/sphinxcontrib-mermaid@0.3.1...0.4.0)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>