Routersploit uses deprecated module telnetlib (removed in Python 3.13)

Hello,

routersploit import the deprecated Python module telnetlib in:
* routersploit/core/telnet/telnet_client.py
* routersploit/core/exploit/shell.py

This module is removed in Python 3.13. The suggested replacements are [telnetlib3](https://pypi.org/project/telnetlib3/), [Exscript](https://pypi.org/project/Exscript/)
See:
https://peps.python.org/pep-0594/#id4
