Add a note to CONTRIBUTING.md about m1 macs

Created by: PatrickRice-KSC

Feature Description

Currently the EE container for GitLab has issues running on m1 macs because there is no native ARM container. We should add a note to our contributing file noting we're aware of this, and we suggest using GitPod to work around it.

Do you want to implement this?

• I would like to implement this myself 👷