build v8.1 with go1.21 fail

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

1、using goland check out v8.1
2、using gvm download a go1.21
3、make

### 2. What did you expect to see? (Required)
build ok

### 3. What did you see instead (Required)
build with warinning

### 4. What is your TiDB version? (Required)
v8.1

Reproduce the v8.1 build using GoLand, gvm with Go 1.21, and make, then inspect the warning shown in the attached image. Confirm the expected result by determining whether the build completes cleanly without the reported warning.

Written by the indexing model from the issue text.