Build(deps-dev): bump gatsby from 3.1.2 to 3.2.1 (#6362)

Bumps [gatsby](https://github.com/gatsbyjs/gatsby) from 3.1.2 to 3.2.1.
- [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/gatsby@3.1.2...gatsby@3.2.1)

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

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