📓 Docker Compose version key is not required after 3.7

From version 3.8 of the compose file specification the version key is no longer required. However, it can be kept for information, if so desired.

In order to run 3.8+ Docker Engine 19.03.0+ is required, see the compatibility matrix for details.

The latest Compose file specification is a merging of the 2.x and 3.x versions and should be the preferred option.