Fix http-response/content-type

[jramosg]

Updated the handler to use the correct response utility from the ring library.
This prevents clj-kondo warningring.util.http-response/content-type unresolved var, although it is really available

https://github.com/metosin/ring-http-response

created and not-found are same in both packages. Also rest of the public vars in ring.util.response are available via ring.util.http-response. These include: status, header, file-response, content-type, find-header, get-header, update-header, charset, set-cookie, response? resource-data, url-response and resource-response.