Update dependency postcss-cli to v7

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
postcss-cli	dependencies	major	^5.0.1 -> ^7.0.0

:information_source: Find our documentation at https://github.com/Financial-Times/next/wiki/Renovate.

---

Release Notes

postcss/postcss-cli

### [`v7.1.0`](https://togithub.com/postcss/postcss-cli/blob/master/CHANGELOG.md#​710--2020-01-09) [Compare Source](https://togithub.com/postcss/postcss-cli/compare/7.0.0...7.1.0) - Respect `map.annotation` option when set to a string ([#​307](https://togithub.com/postcss/postcss-cli/pull/307)) ### [`v7.0.0`](https://togithub.com/postcss/postcss-cli/blob/master/CHANGELOG.md#​700--2020-01-07) [Compare Source](https://togithub.com/postcss/postcss-cli/compare/6.1.3...7.0.0) - **BREAKING:** Drop support for Node 6 & 8 - Update `globby`, which may be a breaking change for a small number of users using certain glob patterns, see for details ([#​303](https://togithub.com/postcss/postcss-cli/pull/303)) - Update dependencies ### [`v6.1.3`](https://togithub.com/postcss/postcss-cli/blob/master/CHANGELOG.md#​613--2019-07-08) [Compare Source](https://togithub.com/postcss/postcss-cli/compare/6.1.2...6.1.3) - Fix external sorcemap filenames when the directory name contains `.css` ([#​283](https://togithub.com/postcss/postcss-cli/issues/283), [#​286](https://togithub.com/postcss/postcss-cli/pull/286)) ### [`v6.1.2`](https://togithub.com/postcss/postcss-cli/blob/master/CHANGELOG.md#​612--2019-02-22) [Compare Source](https://togithub.com/postcss/postcss-cli/compare/6.1.1...6.1.2) - Upgrade dependency globby to fix bug in sub-dependency ([#​265](https://togithub.com/postcss/postcss-cli/issues/265), [#​270](https://togithub.com/postcss/postcss-cli/pull/270)) ### [`v6.1.1`](https://togithub.com/postcss/postcss-cli/blob/master/CHANGELOG.md#​611--2019-01-04) [Compare Source](https://togithub.com/postcss/postcss-cli/compare/6.1.0...6.1.1) - Fix empty lines being printed in some cases ([#​256](https://togithub.com/postcss/postcss-cli/issues/256), [#​257](https://togithub.com/postcss/postcss-cli/pull/257)) ### [`v6.1.0`](https://togithub.com/postcss/postcss-cli/blob/master/CHANGELOG.md#​610--2018-12-19) [Compare Source](https://togithub.com/postcss/postcss-cli/compare/6.0.1...6.1.0) - Add `--include-dotfiles` flag to allow globs to match dotfiles. ([#​254](https://togithub.com/postcss/postcss-cli/pull/254)) - Only log warning messages. This has always been intended behavior, but it wasn't working as expected. ([#​244](https://togithub.com/postcss/postcss-cli/pull/244)) ### [`v6.0.1`](https://togithub.com/postcss/postcss-cli/blob/master/CHANGELOG.md#​601--2018-10-17) [Compare Source](https://togithub.com/postcss/postcss-cli/compare/6.0.0...6.0.1) - Better error handling for errors thrown by plugins ([#​242](https://togithub.com/postcss/postcss-cli/issues/242), [#​243](https://togithub.com/postcss/postcss-cli/pull/243)) - Update dependencies - Clarify docs ([#​233](https://togithub.com/postcss/postcss-cli/issues/233)) ### [`v6.0.0`](https://togithub.com/postcss/postcss-cli/blob/master/CHANGELOG.md#​600--2018-07-18) [Compare Source](https://togithub.com/postcss/postcss-cli/compare/v5.0.1...6.0.0) - Drop support for Node 4 - Upgrade to postcss v7 ([release notes](https://togithub.com/postcss/postcss/blob/master/CHANGELOG.md#​70-president-amy)) - Upgrade to postcss-load-config v2 ([release notes](https://togithub.com/michael-ciniawsky/postcss-load-config/blob/master/CHANGELOG.md#​200-2018-07-10))

---

Renovate configuration

:date: Schedule: At any time (no schedule defined).

:vertical_traffic_light: Automerge: Disabled by config. Please merge this manually once you are satisfied.

:recycle: Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

:no_bell: Ignore: Close this PR and you won't be reminded about this update again.

---

• [ ] If you want to rebase/retry this PR, check this box

---

This PR has been generated by WhiteSource Renovate. View repository job log here.