Bump fs-extra to 9.x

[stianjensen]

This gets in some performance improvements, as well as upgrades underlying dependencies to newer versions.

Bumping to 9.x will require nodejs 10.x as a minimum version, which is already the minimum version declared in package.json.

https://github.com/jprichardson/node-fs-extra/blob/master/CHANGELOG.md

[orta]

Yeah, doing a lower version is better IMO - this isn't a good enough reason to force a semver major on everyone using patch-package

[stianjensen]

Changed to update to 9.x

[orta]

Looks good to me, thanks!

[ds300]

Released in v6.5.1, thanks for the contribution 🎉 ❤️