Update dependency mocha to v2.4.0

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
mocha (source)	'2.3.0' -> '2.4.0'

---

Release Notes

freerange/mocha (mocha)

### [`v2.4.0`](https://togithub.com/freerange/mocha/compare/v2.3.0...v2.4.0) [Compare Source](https://togithub.com/freerange/mocha/compare/v2.3.0...v2.4.0)

---

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• [ ] If you want to rebase/retry this PR, check this box

---

This PR has been generated by Mend Renovate. View repository job log here.

[yegor256]

@rultor please, try to merge, since 4 checks have passed

[rultor]

@rultor please, try to merge, since 4 checks have passed

@yegor256 OK, I'll try to merge now. You can check the progress of the merge here

[rultor]

@rultor please, try to merge, since 4 checks have passed

@yegor256 Done! FYI, the full log is here (took me 8min)