Bump npm from 6.10.1 to 6.13.4
Bump npm from 6.10.1 to 6.13.4

Bumps [npm](https://github.com/npm/cli) from 6.10.1 to 6.13.4.
- [Release notes](https://github.com/npm/cli/releases)
- [Changelog](https://github.com/npm/cli/blob/latest/CHANGELOG.md)
- [Commits](https://github.com/npm/cli/compare/v6.10.1...v6.13.4)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
runk/node-chardet,runk/node-chardet