Explicit top-level namespace reference

[c960657]

Description

Use top-level constant operator to reference root namespace.

Fixes the issue raised by @stanley90 in #1624 (comment). I cannot reproduce it, but I assume it is an issue triggered by Zeitwerk or autoload.

[olleolleolle]

Thanks, @c960657 !

[stanley90]

Hi, I encountered it when I enabled the response logger while debugging something (with json response).
(f.response :logger, nil, { headers: false, bodies: { request: true, response: false }, errors: true })