chore: change URI.encode to URI.encode_www_form
chore: change URI.encode to URI.encode_www_form

fixes #16 

I see @hcatlin beat me to the issue, but this should fix the error messages.

https://docs.knapsackpro.com/2020/uri-escape-is-obsolete-percent-encoding-your-query-string
buttercms/buttercms-ruby