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

[LittleFall]

Bug Report

• 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:

pingcap/tiflash#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