Update nyc to version 6.4.2 🚀

[greenkeeperio-bot]

Hello 👋

🚀🚀🚀

nyc just published its new version 6.4.2, which is not covered by your current version range.

If this pull request passes your tests you can publish your software with the latest version of nyc – otherwise use this branch to work on adaptions and fixes.

Happy fixing and merging 🌴

---

The new version differs by 191 commits .

• 1b625ff chore(release): 6.4.2
• bda6727 chore: upgrade standard-version
• b16053c fix: upgrade spawn-wrap to version that works with new shelljs (#242)
• 24f55e7 fix(update): update strip-bom to version 3.0.0 (#240)
• 693b797 chore(release): 6.4.1
• af0df0c docs: slight tweak to README
• 0946f82 fix: strip any duplicate extensions from --extension (#237)
• f775a2e docs: provide codecov instructions (#233)
• f320bc6 chore(package): update standard-version to version 2.1.2 (#228)
• ea544ef chore: increase test timeout
• f44e454 docs: switch to new badge
• b8ac5ee chore(release): 6.4.0
• f8a02b4 feat(cli): --include and --exclude are now accepted as CLI options, thanks @rpominov \o/ see #207
• de5ca18 chore(package): update standard-version to version 2.1.1
• 3403ca1 fix: adds CLI integration testing, where there was no integration testing before.

There are 191 commits in total. See the full diff.

---

This pull request was created by greenkeeper.io.
It keeps your software up to date, all the time.

_{Tired of seeing this sponsor message? Upgrade to the supporter plan! You'll also get your pull requests faster ⚡}

[coveralls]

Coverage remained the same at 99.569% when pulling 25c7438 on greenkeeper-nyc-6.4.2 into ceae0a2 on master.