fix(deps): update dependency gatsby-source-contentful to v4

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
gatsby-source-contentful	3.1.3 -> 4.1.0

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Release Notes

gatsbyjs/gatsby

### [`v4.1.0`](https://togithub.com/gatsbyjs/gatsby/compare/868bf56c732314fd356e9a082402d6ed73d236de...90d9440bcd44c2b6d70c78bd30adc8c0eec90fc6) [Compare Source](https://togithub.com/gatsbyjs/gatsby/compare/135e554aa9e8f10a282983eca65c29ffae738339...3d607f1ae0cdde12fb8de53e6d0784f83875df25) ### [`v4.0.0`](https://togithub.com/gatsbyjs/gatsby/compare/7a62bc53a72e8e77dafd8f0e74c824332231e819...fe152d879a2abc4973bf4d1f5533f08dec49ab6d) [Compare Source](https://togithub.com/gatsbyjs/gatsby/compare/30dad2b19e0989e3b6b2dfd3388fa10ce8f88de5...135e554aa9e8f10a282983eca65c29ffae738339)

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