Bump acorn from 6.3.0 to 6.4.1 Bumps [acorn](https://github.com/acornjs/acorn) from 6.3.0 to 6.4.1. - [Release notes](https://github.com/acornjs/acorn/releases) - [Commits](https://github.com/acornjs/acorn/compare/6.3.0...6.4.1) Signed-off-by: dependabot[bot]