Update version flag output

[digitalghost-dev]

Currently, the poke-cli --latest flag's output is pretty bland and does not fit the project's overall theme.

Also, having both the latest Docker image and GitHub release tag is a bit redundant. In v1.5.2, the -l | --latest flag will only return the current GitHub release tag.

Example:

┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃                              ┃
┃  Latest available version:   ┃
┃  • v1.5.1                    ┃
┃                              ┃
┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛