Whois21

+ Added IP module and fixed some issues with IP and ASN registration data lookup.
+ Modified the functions responsible for getting json data to download the data if the
file exists but is empty.
+ Fixed minor bugs.

+ Added the option to specify the encoding to use for encoding and decoding the data in
in WHOIS class.
+ Added the option to customize the behavior of the WHOIS class when it encounters an
error while encoding or decoding data.
+ Added the feature to automatically detect the encoding of _whois_ response to solve
decoding issues, such as the one mentioned in issue 2.

Switched from `setup.py` to `pyproject.toml`.

Added ip-api.com API support.

Fixed KeyboardInterrupt handling with `whois21` command.

Minor Fixes.