Fix ImportError: cannot import name 'main' when binaries are invoked by /usr/bin

[D3vil0p3r]

When ipwhois install the CLI scripts in /usr/bin directory, when invoked, they produce the following error:

Traceback (most recent call last):
  File "/usr/bin/ipwhois_cli", line 5, in <module>
    from ipwhois.scripts.ipwhois_cli import main
ImportError: cannot import name 'main' from 'ipwhois.scripts.ipwhois_cli' (/usr/lib/python3.13/site-packages/ipwhois/scripts/ipwhois_cli.py)

It occurs because the original py scripts lack of main function.

This PR fixes the mentioned error.

[D3vil0p3r]

@secynic can you merge this PR and publish a minor release on GitHub and PyPI?