Update dependency fs-extra to v8

[renovate]

This PR contains the following updates:

Package	Type	Update	Change	References
fs-extra	dependencies	major	^7.0.1 -> ^8.0.0	source

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Release Notes

jprichardson/node-fs-extra

v8.0.1

Compare Source

• Fix bug Maximum call stack size exceeded error in util/stat (#​679)

v8.0.0

Compare Source

NOTE: Node.js v6 support is deprecated, and will be dropped in the next major release.

• Use renameSync() under the hood in moveSync()
• Fix bug with bind-mounted directories in copy*() (#​613, #​618)
• Fix bug in move() with case-insensitive file systems
• Use fs.stat()'s bigint option in copy*() & move*() where possible (#​657)

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[edmorley]

We don't seem to use any of the altered functionality.