mongo4.1 support

[imhazige]

could you update the docker tag to mongo version 4.1

[Musikolo]

For me any 4.0.x release would work great because it's the latest stable branch available as of today. Version 4.1.x is a preview release branch, which is the base for the forthcoming next stable branch 4.2.x.

Also having a new image for MongoDB 4.0.x in Docker Registry would be awesome:

• https://hub.docker.com/r/luamas/docker-mongo-local-replicaset/

Thank you!