[submodule] Update submodule sonic-gnmi to the latest HEAD automatically (sonic-net#20864)

#### Why I did it
src/sonic-gnmi
```
* 2c4b9c8 - (HEAD -> master, origin/master, origin/HEAD) Add swss-common log level support to gnmi (sonic-net#330) (21 hours ago) [Hua Liu]
* d77883d - Merge pull request sonic-net#309 from wumiaont/master (24 hours ago) [Rita Hui]
|\ 
| failure_prs.log 80067ec - Fix a panic by gnmi subscribe with invalid xpath (5 weeks ago) [wumiao]
* e6bc0e7 - Add cert CRL support. (sonic-net#269) (3 days ago) [Hua Liu]
```
#### How I did it
#### How to verify it
#### Description for the changelog

Author: mssonicbld