Error with Ember v3.12: You cannot create an Ember Array with `new A()`, please update to calling A as a function: `A()`

**Describe the bug**
It throws the error `You cannot create an Ember Array with new A(), please update to calling A as a function: A()` when using ember-cli-materialize with Ember v3.12 or higher.

**To Reproduce**
Steps to reproduce the behavior:
1. Use ember-cli-materialize with a webapp with Ember v.3.12

I'm going to do a PR with the changes :smile:.
