ti-chi won't decrease LGTM count when lgtm is dismissed.

[LittleFall]

Bug Report

• [x] I have searched the issues of this repository and believe that this is not a duplicate.

Related link

• Which project:

tiflash, maybe all.

• PR or Issue Link:

https://github.com/pingcap/tiflash/pull/5957

Steps to reproduce(Optional)

What is expected?

tichi remove label lgt2 and add label lgt1

What is actually happening?

nothing happend

[ti-chi-bot]

Issues go stale after 90d of inactivity. Mark the issue as fresh with /remove-lifecycle stale. Stale issues rot after an additional 30d of inactivity and eventually close. If this issue is safe to close now please do so with /close. Send feedback to sig-community-infra or Mini256. /lifecycle stale

[ti-chi-bot]

Stale issues rot after 30d of inactivity. Mark the issue as fresh with /remove-lifecycle rotten. Rotten issues close after an additional 30d of inactivity. If this issue is safe to close now please do so with /close. Send feedback to sig-community-infra or Mini256. /lifecycle rotten