Simple-dhcp-server

For a list of changes, please refer to the [Changelog](https://github.com/niccokunzmann/python_dhcp_server?tab=readme-ov-file#changelog).

- add icon to exe file
- add icon to application
- add flatpak build metadata

- Make test field expandable
- Show error message if DHCP port cannot be accessed

- Prevent duplicate assignment of IP addresses
- Add sliders to the GUI


- fixed 12
- desktop file for linux
- documentation improvements

* Update `dhcp.py` and propose another solving method regarding to issue 7