Update dependency read-pkg-up to v8

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
read-pkg-up	^7.0.0 -> ^8.0.0

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Release Notes

sindresorhus/read-pkg-up

### [`v8.0.0`](https://togithub.com/sindresorhus/read-pkg-up/releases/v8.0.0) [Compare Source](https://togithub.com/sindresorhus/read-pkg-up/compare/v7.0.1...v8.0.0) ##### Breaking - Require Node.js 12 and move to ESM [`e6fbe7f`](https://togithub.com/sindresorhus/read-pkg-up/commit/e6fbe7f) - This package now exports two named exports instead of a default export [`e6fbe7f`](https://togithub.com/sindresorhus/read-pkg-up/commit/e6fbe7f) - This package is now pure ESM. Please [read this](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c).

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