fix(deps): update gatsby monorepo

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
gatsby (changelog)	dependencies	patch	2.24.72 -> 2.24.73
gatsby-plugin-react-helmet	dependencies	patch	3.3.13 -> 3.3.14
gatsby-plugin-sharp	dependencies	patch	2.6.39 -> 2.6.40

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Release Notes

gatsbyjs/gatsby

### [`v2.24.73`](https://togithub.com/gatsbyjs/gatsby/compare/gatsby@2.24.72...gatsby@2.24.73) [Compare Source](https://togithub.com/gatsbyjs/gatsby/compare/gatsby@2.24.72...gatsby@2.24.73)

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