npm audit fix (#192)

This change is generated by the `npm audit fix` command.

Fixed vulnerable dependencies:

```
browserslist  4.0.0 - 4.16.4
Severity: moderate
Regular Expression Denial of Service - https://npmjs.com/advisories/1747

hosted-git-info  <2.8.9 || >=3.0.0 <3.0.8
Severity: moderate
Regular Expression Denial of Service - https://npmjs.com/advisories/1677

y18n  <3.2.2||=4.0.0||>=5.0.0 <5.0.5
Severity: high
Prototype Pollution - https://npmjs.com/advisories/1654
```

See also #191