chore(deps): update dependency rollup-plugin-postcss to v3

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
rollup-plugin-postcss	devDependencies	major	2.5.0 -> 3.1.2

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Release Notes

egoist/rollup-plugin-postcss

### [`v3.1.2`](https://togithub.com/egoist/rollup-plugin-postcss/releases/v3.1.2) [Compare Source](https://togithub.com/egoist/rollup-plugin-postcss/compare/v3.1.1...v3.1.2) ##### Bug Fixes - replace const keyword with var keyword in output ([#​283](https://togithub.com/egoist/rollup-plugin-postcss/issues/283)) ([a5fd035](https://togithub.com/egoist/rollup-plugin-postcss/commit/a5fd035a161707e0e0ce583d827f619d6cf8e7bc)) ### [`v3.1.1`](https://togithub.com/egoist/rollup-plugin-postcss/releases/v3.1.1) [Compare Source](https://togithub.com/egoist/rollup-plugin-postcss/compare/v3.1.0...v3.1.1) ##### Bug Fixes - revert "feat: allow multiple entry files and outputs ([#​264](https://togithub.com/egoist/rollup-plugin-postcss/issues/264))" ([#​272](https://togithub.com/egoist/rollup-plugin-postcss/issues/272)) ([b17c15d](https://togithub.com/egoist/rollup-plugin-postcss/commit/b17c15d0942ba053f053d70c18529cb27c126e72)) ### [`v3.1.0`](https://togithub.com/egoist/rollup-plugin-postcss/releases/v3.1.0) [Compare Source](https://togithub.com/egoist/rollup-plugin-postcss/compare/v3.0.0...v3.1.0) ##### Features - allow multiple entry files and outputs ([#​264](https://togithub.com/egoist/rollup-plugin-postcss/issues/264)) ([3ea986c](https://togithub.com/egoist/rollup-plugin-postcss/commit/3ea986c83b9f292fc80017381820ba236fff008d)) ### [`v3.0.0`](https://togithub.com/egoist/rollup-plugin-postcss/releases/v3.0.0) [Compare Source](https://togithub.com/egoist/rollup-plugin-postcss/compare/1a6ab380f1b264a7eedacd029a3cae4cbe7f8c9e...v3.0.0) ##### Documentation - add v3 usage ([#​268](https://togithub.com/egoist/rollup-plugin-postcss/issues/268)) ([b27c3eb](https://togithub.com/egoist/rollup-plugin-postcss/commit/b27c3ebef47d32420b98ab03cab9aa2fe1ae5891)) ##### BREAKING CHANGES - v3 not support rollup v1. extract relative path based on bundle root. ### [`v2.9.0`](https://togithub.com/egoist/rollup-plugin-postcss/compare/v2.8.2...1a6ab380f1b264a7eedacd029a3cae4cbe7f8c9e) [Compare Source](https://togithub.com/egoist/rollup-plugin-postcss/compare/v2.8.2...1a6ab380f1b264a7eedacd029a3cae4cbe7f8c9e) ### [`v2.8.2`](https://togithub.com/egoist/rollup-plugin-postcss/releases/v2.8.2) [Compare Source](https://togithub.com/egoist/rollup-plugin-postcss/compare/v2.8.1...v2.8.2) ##### Bug Fixes - extract relative path ([#​262](https://togithub.com/egoist/rollup-plugin-postcss/issues/262)) ([0e71f75](https://togithub.com/egoist/rollup-plugin-postcss/commit/0e71f751ae4bca266715971065b29a5ed5941dd0)) ### [`v2.8.1`](https://togithub.com/egoist/rollup-plugin-postcss/releases/v2.8.1) [Compare Source](https://togithub.com/egoist/rollup-plugin-postcss/compare/v2.6.4...v2.8.1) ##### Bug Fixes - AssetInfo modules used for chunk ([df71f37](https://togithub.com/egoist/rollup-plugin-postcss/commit/df71f37f9adc68d27fe9e162dba5ebba5b7e644f)) ### [`v2.6.4`](https://togithub.com/egoist/rollup-plugin-postcss/releases/v2.6.4) [Compare Source](https://togithub.com/egoist/rollup-plugin-postcss/compare/v2.6.2...v2.6.4) ##### Bug Fixes - package.json version ([437170b](https://togithub.com/egoist/rollup-plugin-postcss/commit/437170b057ae7f0fad9dd5730da57f51f3280430)) ### [`v2.6.2`](https://togithub.com/egoist/rollup-plugin-postcss/releases/v2.6.2) [Compare Source](https://togithub.com/egoist/rollup-plugin-postcss/compare/v2.6.1...v2.6.2) ##### Bug Fixes - resolve typo ([026504e](https://togithub.com/egoist/rollup-plugin-postcss/commit/026504ef0480910e830873c30c5b133e2a130a64)) ### [`v2.6.1`](https://togithub.com/egoist/rollup-plugin-postcss/releases/v2.6.1) [Compare Source](https://togithub.com/egoist/rollup-plugin-postcss/compare/v2.5.0...v2.6.1) ##### Bug Fixes - package.json version ([75306fb](https://togithub.com/egoist/rollup-plugin-postcss/commit/75306fb54307573dbad9438da92664ced74c63e3))

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