Bump postcss, autoprefixer, cssnano, gulp-postcss, postcss-calc, postcss-custom-properties, postcss-import, postcss-url and stylelint

Bumps [postcss](https://github.com/postcss/postcss) to 8.5.19 and updates ancestor dependencies [postcss](https://github.com/postcss/postcss), [autoprefixer](https://github.com/postcss/autoprefixer), [cssnano](https://github.com/cssnano/cssnano), [gulp-postcss](https://github.com/postcss/gulp-postcss), [postcss-calc](https://github.com/postcss/postcss-calc), [postcss-custom-properties](https://github.com/csstools/postcss-plugins/tree/HEAD/plugins/postcss-custom-properties), [postcss-import](https://github.com/postcss/postcss-import), [postcss-url](https://github.com/postcss/postcss-url) and [stylelint](https://github.com/stylelint/stylelint). These dependencies need to be updated together.


Updates `postcss` from 7.0.35 to 8.5.19
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@7.0.35...8.5.19)

Updates `autoprefixer` from 9.8.6 to 10.5.4
- [Release notes](https://github.com/postcss/autoprefixer/releases)
- [Changelog](https://github.com/postcss/autoprefixer/blob/main/CHANGELOG.md)
- [Commits](postcss/autoprefixer@9.8.6...10.5.4)

Updates `cssnano` from 4.1.10 to 8.0.2
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/v4.1.10...cssnano@8.0.2)

Updates `gulp-postcss` from 8.0.0 to 10.0.0
- [Release notes](https://github.com/postcss/gulp-postcss/releases)
- [Commits](postcss/gulp-postcss@8.0.0...10.0.0)

Updates `postcss-calc` from 7.0.5 to 10.1.1
- [Release notes](https://github.com/postcss/postcss-calc/releases)
- [Changelog](https://github.com/postcss/postcss-calc/blob/master/CHANGELOG.md)
- [Commits](postcss/postcss-calc@v7.0.5...v10.1.1)

Updates `postcss-custom-properties` from 9.1.1 to 15.0.1
- [Changelog](https://github.com/csstools/postcss-plugins/blob/main/plugins/postcss-custom-properties/CHANGELOG.md)
- [Commits](https://github.com/csstools/postcss-plugins/commits/HEAD/plugins/postcss-custom-properties)

Updates `postcss-import` from 12.0.1 to 16.1.1
- [Release notes](https://github.com/postcss/postcss-import/releases)
- [Changelog](https://github.com/postcss/postcss-import/blob/master/CHANGELOG.md)
- [Commits](postcss/postcss-import@12.0.1...16.1.1)

Updates `postcss-url` from 8.0.0 to 10.1.4
- [Release notes](https://github.com/postcss/postcss-url/releases)
- [Changelog](https://github.com/postcss/postcss-url/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss-url@8.0.0...10.1.4)

Updates `stylelint` from 13.6.1 to 17.14.0
- [Release notes](https://github.com/stylelint/stylelint/releases)
- [Changelog](https://github.com/stylelint/stylelint/blob/main/CHANGELOG.md)
- [Commits](stylelint/stylelint@13.6.1...17.14.0)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.19
  dependency-type: indirect
- dependency-name: autoprefixer
  dependency-version: 10.5.4
  dependency-type: direct:development
- dependency-name: cssnano
  dependency-version: 8.0.2
  dependency-type: direct:development
- dependency-name: gulp-postcss
  dependency-version: 10.0.0
  dependency-type: direct:development
- dependency-name: postcss-calc
  dependency-version: 10.1.1
  dependency-type: direct:development
- dependency-name: postcss-custom-properties
  dependency-version: 15.0.1
  dependency-type: direct:development
- dependency-name: postcss-import
  dependency-version: 16.1.1
  dependency-type: direct:development
- dependency-name: postcss-url
  dependency-version: 10.1.4
  dependency-type: direct:development
- dependency-name: stylelint
  dependency-version: 17.14.0
  dependency-type: direct:development
...

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Author: dependabot[bot]