Update dependency load-grunt-tasks to v4

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change	References
load-grunt-tasks	devDependencies	major	3.5.2 -> 4.0.0	source

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Release Notes

sindresorhus/load-grunt-tasks

### [`v4.0.0`](https://renovatebot.com/gh/sindresorhus/load-grunt-tasks/compare/v3.5.2...v4.0.0) [Compare Source](https://renovatebot.com/gh/sindresorhus/load-grunt-tasks/compare/v3.5.2...v4.0.0)

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