Bump broccoli-concat from 3.7.3 to 3.7.4
Bump broccoli-concat from 3.7.3 to 3.7.4

Bumps [broccoli-concat](https://github.com/ember-cli/broccoli-concat) from 3.7.3 to 3.7.4.
- [Release notes](https://github.com/ember-cli/broccoli-concat/releases)
- [Changelog](https://github.com/broccolijs/broccoli-concat/blob/master/CHANGELOG.md)
- [Commits](https://github.com/ember-cli/broccoli-concat/compare/v3.7.3...v3.7.4)

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