build(deps-dev): bump lerna from 6.1.0 to 6.4.0

Bumps [lerna](https://github.com/lerna/lerna/tree/HEAD/core/lerna) from 6.1.0 to 6.4.0.
- [Release notes](https://github.com/lerna/lerna/releases)
- [Changelog](https://github.com/lerna/lerna/blob/main/core/lerna/CHANGELOG.md)
- [Commits](https://github.com/lerna/lerna/commits/v6.4.0/core/lerna)

---
updated-dependencies:
- dependency-name: lerna
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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