Build(deps-dev): bump gatsby-plugin-remove-trailing-slashes (#4215)

Bumps [gatsby-plugin-remove-trailing-slashes](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-remove-trailing-slashes) from 2.1.10 to 2.1.12.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-remove-trailing-slashes/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/gatsby-plugin-remove-trailing-slashes@2.1.12/packages/gatsby-plugin-remove-trailing-slashes

)

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