Update dependency autoprefixer to v10

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
autoprefixer	9.8.6 -> 10.0.4

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Release Notes

postcss/autoprefixer

### [`v10.0.4`](https://togithub.com/postcss/autoprefixer/blob/master/CHANGELOG.md#​1004) [Compare Source](https://togithub.com/postcss/autoprefixer/compare/10.0.3...10.0.4) - Fixed `Cannot read property 'proxyOf' of undefined` error (by Igor Kamyshev). ### [`v10.0.3`](https://togithub.com/postcss/autoprefixer/blob/master/CHANGELOG.md#​1003) [Compare Source](https://togithub.com/postcss/autoprefixer/compare/10.0.2...10.0.3) - Fixed `substract` to `subtract` value for `mask-composite` (by Michelle Enos). ### [`v10.0.2`](https://togithub.com/postcss/autoprefixer/blob/master/CHANGELOG.md#​1002) [Compare Source](https://togithub.com/postcss/autoprefixer/compare/10.0.1...10.0.2) - Removed `-ms-user-select: all` because IE and old Edge don’t support it. - Fixed Grid Layout warning. ### [`v10.0.1`](https://togithub.com/postcss/autoprefixer/blob/master/CHANGELOG.md#​1001) [Compare Source](https://togithub.com/postcss/autoprefixer/compare/10.0.0...10.0.1) - Fix PostCSS 8.1 compatability. - Add our OpenCollective to `package.json`. - Clean up code (by Sukka). ### [`v10.0.0`](https://togithub.com/postcss/autoprefixer/releases/10.0.0) [Compare Source](https://togithub.com/postcss/autoprefixer/compare/9.8.6...10.0.0) Autoprefixer 10 is based on top of [PostCSS 8](https://togithub.com/postcss/postcss/releases/tag/8.0.0) (check **Known Issues** section before updating). Node.js 6.x, 8.x, 11.x support was removed. Now you need to install Autoprefixer by `npm install --save-dev autoprefixer postcss`. We moved `postcss` from `dependencies` to `peerDependencies` according to [new PostCSS plugin guidelines](https://togithub.com/postcss/postcss/blob/master/docs/guidelines/plugin.md).

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