fix(deps): update dependency find-up to v4

[renovate]

This PR contains the following updates:

Package	Type	Update	Change	References
find-up	dependencies	major	3.0.0 -> 4.0.0	source

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Release Notes

sindresorhus/find-up

v4.0.0

Compare Source

Breaking:

• Require Node.js 8 80fda88
• Return undefined instead of null when the path cannot be found a7a9500
• Add ability to specify if looking for file or directory (#​40) da17a22
  It now only matches files by default, not also directories. Previously it would match either.

Enhancements:

• Add support for path matcher function (#​28) c0f0dd7
• Add TypeScript definition (#​35) 905e612

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[coveralls]

Coverage remained the same at 100.0% when pulling c9e1efa on renovate/find-up-4.x into 32370d6 on master.