Remove colon in output filename as it is a Windows bad char

[maaaaz]

Hello again,

I'm often using your cool tool from a Linux VM writing on a Windows file share, and I had to replace the colon from the output filename with a underscore
https://github.com/ropnop/windapsearch/blob/master/windapsearch.py#L510

Would you patch it ? :)

Cheers!