Update dependency grunt-eslint to v22 - autoclosed

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
grunt-eslint	devDependencies	major	^21.0.0 -> ^22.0.0

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Release Notes

sindresorhus/grunt-eslint

### [`v22.0.0`](https://togithub.com/sindresorhus/grunt-eslint/releases/v22.0.0) [Compare Source](https://togithub.com/sindresorhus/grunt-eslint/compare/v21.1.0...v22.0.0) Breaking: - Upgrade to [ESLint 6](https://eslint.org/blog/2019/06/eslint-v6.0.0-released) [`7707f60`](https://togithub.com/sindresorhus/grunt-eslint/commit/7707f60) - Require Node.js 8 [`7707f60`](https://togithub.com/sindresorhus/grunt-eslint/commit/7707f60)

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Renovate configuration

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