fix(deps): update gatsby monorepo

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
gatsby (changelog)	2.27.3 -> 2.27.4
gatsby-plugin-sharp	2.7.1 -> 2.9.1
gatsby-transformer-sharp	2.5.21 -> 2.7.0

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Release Notes

gatsbyjs/gatsby

### [`v2.27.4`](https://togithub.com/gatsbyjs/gatsby/compare/gatsby@2.27.3...gatsby@2.27.4) [Compare Source](https://togithub.com/gatsbyjs/gatsby/compare/gatsby@2.27.3...gatsby@2.27.4)

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