Update devDependencies

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
open-props	1.5.11 -> 1.5.13
postcss (source)	8.4.27 -> 8.4.28

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Release Notes

argyleink/open-props (open-props)

### [`v1.5.13`](https://togithub.com/argyleink/open-props/compare/b02b1a8fd2953e34b25d1abc6b557f573c1a67c0...e6853ca7ce8e0ff10a9110034363c6506d3363e5) [Compare Source](https://togithub.com/argyleink/open-props/compare/b02b1a8fd2953e34b25d1abc6b557f573c1a67c0...e6853ca7ce8e0ff10a9110034363c6506d3363e5)

postcss/postcss (postcss)

### [`v8.4.28`](https://togithub.com/postcss/postcss/blob/HEAD/CHANGELOG.md#8428) [Compare Source](https://togithub.com/postcss/postcss/compare/8.4.27...8.4.28) - Fixed `Root.source.end` for better source map (by Romain Menke). - Fixed `Result.root` types when `process()` has no parser.

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