feat: use supported version of Unity docker image
feat: use supported version of Unity docker image

2019.4.14f1-windows
- https://hub.docker.com/layers/gableroux/unity3d/2019.4.14f1-windows/images/sha256-86c6bf88c6ff8a50dc9087e97492b9af0b9a54d778153a63c188ab3ac8a8efec

snackpackgames/Rubbley