[enhancement] Update mocha from v3.2.0 to v6.1.3

[bjornstar]

PR checklist

• New feature, bugfix, or enhancement

Overview of change:

Update mocha from v3.2.0 to v6.1.3
Update @types/mocha from v2.2.35 to v5.2.6

Is there anything you'd like reviewers to focus on?

This addresses the following security audit issues related to mocha:

                       === npm audit security report ===                        
                                                                                
# Run  npm install --save-dev [email protected]  to resolve 2 vulnerabilities
SEMVER WARNING: Recommended action is a potentially breaking change
┌───────────────┬──────────────────────────────────────────────────────────────┐
│ Low           │ Regular Expression Denial of Service                         │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Package       │ debug                                                        │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Dependency of │ mocha [dev]                                                  │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Path          │ mocha > debug                                                │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ More info     │ https://npmjs.com/advisories/534                             │
└───────────────┴──────────────────────────────────────────────────────────────┘


┌───────────────┬──────────────────────────────────────────────────────────────┐
│ Critical      │ Command Injection                                            │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Package       │ growl                                                        │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Dependency of │ mocha [dev]                                                  │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Path          │ mocha > growl                                                │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ More info     │ https://npmjs.com/advisories/146                             │
└───────────────┴──────────────────────────────────────────────────────────────┘

CHANGELOG.md entry:

[chore] Update mocha from v3.2.0 to v6.1.3

[adidahiya]

lint and lockfile issues... but otherwise upgrading mocha sounds like a good idea

[bjornstar]

Done!

[adidahiya]

nice, thanks!