nmap is not nmap

Hi, I noticed that this project has a dependency on nmap in requirements.txt. [It was brought to my attention](https://github.com/antonagestam/nmap/issues/2#issuecomment-1510389863) that people mistakenly install this in belief it's the well-known port scanning tool, which it's not. I've since removed the single release of my nmap library from PyPI, and so wanted to inform you that installation is likely to break until you remove this dependency (which I assume was incorrectly added to begin with). Sorry for any inconvenience caused by this.