added several site and removed duplicates

[sharifulgeo]

1. Added https://freeproxy.lunaproxy.com/
2. Added https://raw.githubusercontent.com/proxifly/free-proxy-list/main/proxies/all/data.txt which periodically updates within 5 minutes.
3. Added https://raw.githubusercontent.com/monosans/proxy-list/main/proxies/all.txt which also updates periodically. It is also maintained by creator of linux- Linus Torvalds
4. Some site contains duplicate proxy. So, I rechecked and removed duplicate proxies before writing to file.

[iw4p]

Hello!
Thank you for the contribution! Can you please run flake8 . to make sure there's no error to fix the checks?

[sharifulgeo]

Hello! Thank you for the contribution! Can you please run flake8 . to make sure there's no error to fix the checks?

flaked the code.

[iw4p]

Thank you!