fix: return response body from revoke! for logging pipeline

[katsu223]

Fixes a bug in UserRefreshCredentials.revoke! where the method was returning an integer (0) instead of the response body, causing JSON parsing errors in log_response.

Fixes: #540

[viacheslav-rostovtsev]

Hello! Thank you for raising the issue and implementing a fix. While looking into it I've also noticed that the log_response method itself never invokes the logger. I've changed that (will now log at debug) and pushed a commit to your branch (there are also tests for logging and execution speedups).

LMK if you would prefer me to do this in a separate PR rather than yours

[katsu223]

Hello! Thank you for raising the issue and implementing a fix. While looking into it I've also noticed that the log_response method itself never invokes the logger. I've changed that (will now log at debug) and pushed a commit to your branch (there are also tests for logging and execution speedups).

LMK if you would prefer me to do this in a separate PR rather than yours

Hello. Thank you for taking an eye on that. I personally don't mind, you may leave changes here