Ruby 3.x support

[EtienneDepaulis]

URI.unescape is obsolete in ruby 3.x:

This method is obsolete and should not be used. Instead, use CGI.escape, URI.encode_www_form or URI.encode_www_form_component depending on your specific use case.

This PR fixes this :)

[swilgosz]

@EtienneDepaulis as you've deleted the original branch, I cannot merge this :( . It simply means, I'll need to re-create the PR, which will not include you as contributors love to avoid that.

[EtienneDepaulis]

@swilgosz my fix was not working :( (I opened the PR a bit too early)
CGI.unescape does not behave like CGI.unescape sadly

[swilgosz]

@EtienneDepaulis Here is the alternative method and the differences explained.

https://stackoverflow.com/questions/30783879/whats-the-difference-between-cgi-unescape-and-uri-decode-www-form-component

Do you plan to continue working on this? :)