fix(deps): update gatsby monorepo to v5.16.0

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
gatsby-plugin-react-helmet	5.15.0 -> 5.16.0
gatsby-plugin-styled-components	5.15.0 -> 5.16.0

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Release Notes

gatsbyjs/gatsby (gatsby-plugin-react-helmet)

### [`v5.16.0`](https://togithub.com/gatsbyjs/gatsby/compare/gatsby-plugin-react-helmet@5.15.0...gatsby-plugin-react-helmet@5.16.0) [Compare Source](https://togithub.com/gatsbyjs/gatsby/compare/gatsby-plugin-react-helmet@5.15.0...gatsby-plugin-react-helmet@5.16.0)

gatsbyjs/gatsby (gatsby-plugin-styled-components)

### [`v5.16.0`](https://togithub.com/gatsbyjs/gatsby/compare/gatsby-plugin-styled-components@5.15.0...gatsby-plugin-styled-components@5.16.0) [Compare Source](https://togithub.com/gatsbyjs/gatsby/compare/gatsby-plugin-styled-components@5.15.0...gatsby-plugin-styled-components@5.16.0)

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Configuration

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