Bumps [acorn](https://github.com/acornjs/acorn) from 5.7.3 to 5.7.4. - [Release notes](https://github.com/acornjs/acorn/releases) - [Commits](https://github.com/acornjs/acorn/compare/5.7.3...5.7.4) Signed-off-by: dependabot[bot] <support@github.com>