Zigbee2mqtt: Docker test image based on Gladys v4

Hello everyone!

For your information, following the changes made by @cicoub13 on the PR, I have conducted a technical and functional review of the PR.

My review report is available on GitHub: https://github.com/GladysAssistant/Gladys/pull/1098#issuecomment-803718817

Edit: I’m also waiting for the fix here: