Revamped installer script

[nicomiguelino]

Hello, there. I'm so excited to announce that we've cosmetically improved and refactored our installation script.
Here's what it looks like in a nutshell:

As seen in this section of README.md, the command to install Anthias is still the same:

$ bash <(curl -sL https://install-anthias.srly.io)

Thanks to @charmbracelet's gum for making this possible.