Update dependency cssnano to v5.0.2

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
cssnano	5.0.1 -> 5.0.2

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Release Notes

cssnano/cssnano

### [`v5.0.2`](https://togithub.com/cssnano/cssnano/releases/cssnano@5.0.2) [Compare Source](https://togithub.com/cssnano/cssnano/compare/cssnano@5.0.1...cssnano@5.0.2) #### Bug Fixes - **postcss-merge-longhand:** mergeLonghand should not apply to CSS variables ([#​1057](https://togithub.com/cssnano/cssnano/issues/1057)) ([8aa64c7](https://togithub.com/cssnano/cssnano/commit/8aa64c714f615db747605f6d79fcc043e9ee8e57)), closes [#​1051](https://togithub.com/cssnano/cssnano/issues/1051)

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Configuration

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