deps: bump the dependency-updates group with 2 updates

Bumps the dependency-updates group with 2 updates: [gatsby](https://github.com/gatsbyjs/gatsby) and [gatsby-plugin-mdx](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-mdx).


Updates `gatsby` from 5.14.1 to 5.14.2
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/compare/[email protected]@5.14.2)

Updates `gatsby-plugin-mdx` from 5.14.0 to 5.14.1
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-mdx/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/[email protected]/packages/gatsby-plugin-mdx)

---
updated-dependencies:
- dependency-name: gatsby
  dependency-version: 5.14.2
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: dependency-updates
- dependency-name: gatsby-plugin-mdx
  dependency-version: 5.14.1
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: dependency-updates
...

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

Author: dependabot[bot]