Update picocli to 4.7.0

[vanitasvitae]

Picocli 4.7.0 will introduce better support for shared resources. Most notably, child commands will inherit resources from their parent commands resource bundle.

This means that once we bump picocli to 4.7.0, all subcommands will inherit the parents footer, exit codes sections.
We might want to keep this in the back of our heads.