Bump the gatsby group with 5 updates

Bumps the gatsby group with 5 updates:

| Package | From | To |
| --- | --- | --- |
| [gatsby](https://github.com/gatsbyjs/gatsby) | `5.12.5` | `5.12.6` |
| [gatsby-plugin-image](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-image) | `3.12.0` | `3.12.1` |
| [gatsby-plugin-sharp](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-sharp) | `5.12.0` | `5.12.1` |
| [gatsby-plugin-sitemap](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-sitemap) | `6.12.0` | `6.12.1` |
| [gatsby-transformer-sharp](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-transformer-sharp) | `5.12.0` | `5.12.1` |


Updates `gatsby` from 5.12.5 to 5.12.6
- [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]@5.12.6)

Updates `gatsby-plugin-image` from 3.12.0 to 3.12.1
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-image/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/[email protected]/packages/gatsby-plugin-image)

Updates `gatsby-plugin-sharp` from 5.12.0 to 5.12.1
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-sharp/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/[email protected]/packages/gatsby-plugin-sharp)

Updates `gatsby-plugin-sitemap` from 6.12.0 to 6.12.1
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-sitemap/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/[email protected]/packages/gatsby-plugin-sitemap)

Updates `gatsby-transformer-sharp` from 5.12.0 to 5.12.1
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-transformer-sharp/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/[email protected]/packages/gatsby-transformer-sharp)

---
updated-dependencies:
- dependency-name: gatsby
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: gatsby
- dependency-name: gatsby-plugin-image
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: gatsby
- dependency-name: gatsby-plugin-sharp
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: gatsby
- dependency-name: gatsby-plugin-sitemap
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: gatsby
- dependency-name: gatsby-transformer-sharp
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: gatsby
...

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