exclude_object: Fix use of deprecated gcmd.respond_error()

[TypQxQ]

gcmd.respond_error() has been deprecated: https://github.com/Klipper3d/klipper/commit/61524542d20e50c4866836d6ed23ca03521ffb15

Signed-off-by: Andrei Ignat andrei@ignat.se

[JamesH1978]

Thanks for the PR, while I can't comment on the actual code i can ask you to please refer to point 3 in "Common things a reviewer will look for:" section in https://github.com/Klipper3d/klipper/blob/master/docs/CONTRIBUTING.md and provide a signed-of-by line

Thanks James

[KevinOConnor]

Thanks.

-Kevin