Fix "URI.escape deprecated" warning with Ruby 2.7+

[BrunoNZ]

Ruby 2.7 prints a lot of warnings of "URI.escape deprecated", in file "http.rb". I've noticed it while updating one project from Ruby 2.6.6 to 2.7.4. The code seems to be working fine still, but the warnings are very annoying. There are some examples of this fix in other projects: https://github.com/rollbar/rollbar-gem/pull/988/files https://github.com/docusign/docusign-esign-ruby-client/issues/45

It would be nice to fix it already and make it ready for newer ruby versions. Thanks!