fix(adk-demo): fix adk demo 3_feedback-loop 'gob type main.FeedbackInfo miss'

[czasg]

fix adk demo 3_feedback-loop 'gob type main.FeedbackInfo miss'

What type of PR is this?

fix: A bug fix

Check the PR title.

pass

(Optional) Translate the PR title into Chinese.

注册 FeedbackInfo 类型，以便 gob 序列化时能够正确处理

(Optional) More detailed description for this PR(en: English/zh: Chinese).

When I was carrying out this demo, it encountered an error.

failed to save checkpoint: failed to encode checkpoint: gob: type not registered for interface: main.FeedbackInfo

(Optional) Which issue(s) this PR fixes:

none

(optional) The PR that updates user documentation:

none

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}