chore(deps): bump npm from 6.14.4 to 6.14.15

Bumps [npm](https://github.com/npm/cli) from 6.14.4 to 6.14.15.
- [Release notes](https://github.com/npm/cli/releases)
- [Changelog](https://github.com/npm/cli/blob/v6.14.15/CHANGELOG.md)
- [Commits](npm/cli@v6.14.4...v6.14.15)

---
updated-dependencies:
- dependency-name: npm
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]