Bump @storybook/addon-mdx-gfm from 7.0.27 to 7.2.1 in /frontend

Bumps [@storybook/addon-mdx-gfm](https://github.com/storybookjs/storybook/tree/HEAD/code/addons/gfm) from 7.0.27 to 7.2.1.
- [Release notes](https://github.com/storybookjs/storybook/releases)
- [Changelog](https://github.com/storybookjs/storybook/blob/next/CHANGELOG.md)
- [Commits](https://github.com/storybookjs/storybook/commits/v7.2.1/code/addons/gfm)

---
updated-dependencies:
- dependency-name: "@storybook/addon-mdx-gfm"
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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