Pull only the latest version of the required Docker images

You are currently pulling all versions which is crazy

• it takes ages for the first macro call to finish
• you force the user to download a couple of GBs of data..

The reason is because you don't use a version tag in your configuration:

"image": "yuzutech/kroki",

What's funny is that you do use a version tag in your tests:

when(this.configuration.getKrokiDockerImage()).thenReturn("yuzutech/kroki:latest");

You need to updated all your configuration to use *:latest.