Update dependencies version to fix security issues

[pmprete]

Bump the version of mocha, yargs and mkdirp to solve the issues shown by npm audit:

npm audit security report

Run npm install yargs@15.3.1 to resolve 1 vulnerability

SEMVER WARNING: Recommended action is a potentially breaking change
│ Low │ Denial of Service
│ Package │ mem
│ Dependency of │ yargs
│ More info │ https://npmjs.com/advisories/1084

Run npm install mocha@7.1.2 to resolve 1 vulnerability

SEMVER WARNING: Recommended action is a potentially breaking change
│ Low │ Prototype Pollution
│ Package │ minimist
│ Dependency of │ mocha
│ Path │ mocha > mkdirp > minimist
│ More info │ https://npmjs.com/advisories/1179

Run npm install mkdirp@1.0.4 to resolve 1 vulnerability

SEMVER WARNING: Recommended action is a potentially breaking change
│ Low │ Prototype Pollution
│ Package │ minimist
│ Dependency of │ mkdirp
│ Path │ mkdirp > minimist
│ More info │ https://npmjs.com/advisories/1179

found 3 low severity vulnerabilities in 88 scanned packages
3 vulnerabilities require semver-major dependency updates.

[duaraghav8]

@pmprete thanks! I'll test it out locally and then merge