Bump acorn from 7.1.0 to 7.1.1

Bumps [acorn](https://github.com/acornjs/acorn) from 7.1.0 to 7.1.1.
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](acornjs/acorn@7.1.0...7.1.1)

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

Author: dependabot[bot]