Add WTFPL license from http://www.wtfpl.net/

[schnoddelbotz]

Hi,

just as proposal.
I have no clue considering licenses ... and this would often be my, uhm, safest bet ;)

Thanks for 🐍 (and viper!)

[CLAassistant]

All committers have signed the CLA.

[github-actions]

This PR is being marked as stale due to a long period of inactivity

[johnSchnake]

From their FAQ:

Is the WTFPL a valid license?
Although the validity of the WTFPL has not been tested in courts, it is widely accepted as a valid license. Every major Linux distribution (Debian, Fedora, Arch, Gentoo, etc.) ships software licensed under the WTFPL, version 1 or 2. Bradley Kuhn (executive director of the Free Software Foundation) was quoted saying that the FSF’s folks agree the WTFPL is a valid free software license.

and confirmed briefly by it being on this list: https://fedoraproject.org/wiki/Licensing:Main#Good_Licenses

I'll defer the final approval to a more seasoned maintainer though. Seems fine to me.

[jpmcb]

Hi all - the cobra CLI tool has moved to: https://github.com/spf13/cobra-cli

Let's close this and open a new PR over there. Sorry for the hassle!