Fix Padrino tests for new Sinatra version
Fix Padrino tests for new Sinatra version

Looks like something changed in Sinatra 2.2.0, released February 15,
2022. The build on main started failing.

Looks like the response body is escaping characters. Update the test to
match.

appsignal/appsignal-ruby,appsignal/appsignal-ruby,appsignal/appsignal-ruby,appsignal/appsignal-ruby