[Security] Bump acorn from 5.4.1 to 5.7.4
[Security] Bump acorn from 5.4.1 to 5.7.4

Bumps [acorn](https://github.com/acornjs/acorn) from 5.4.1 to 5.7.4. **This update includes a security fix.**
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](https://github.com/acornjs/acorn/compare/5.4.1...5.7.4)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
RuslanZavacky/ember-cli-ifa,RuslanZavacky/ember-cli-ifa