[submodule] Update submodule sonic-gnmi to the latest HEAD automatica…

…lly (#18888)

#### Why I did it
src/sonic-gnmi
```
* c2bfe3d - (HEAD -> master, origin/master, origin/HEAD) Fix memory leak in unit test (#230) (44 minutes ago) [ganglv]
* 16c2975 - Disable translib unit test (#229) (71 minutes ago) [ganglv]
* 4c86853 - Merge pull request #224 from ganglyu/fix_build (10 hours ago) [Saikrishna Arcot]
* db2d896 - Disable dialout unit test (3 days ago) [ganglyu]
* 0e4ac4d - Disable translib test (4 days ago) [ganglyu]
* 8494e90 - Fix unit test (4 days ago) [ganglyu]
* 036979d - Fix unit test (4 days ago) [ganglyu]
* bd74b09 - Disable failed unit test (4 days ago) [ganglyu]
* a4bc960 - Update go.mod (7 days ago) [ganglyu]
* c15d45f - Fix build error (7 days ago) [ganglyu]
* 775a41e - Fix go.sum (7 days ago) [ganglyu]
* b39742e - Fix build error from sonic-mgmt-common (7 days ago) [ganglyu]
```
#### How I did it
#### How to verify it
#### Description for the changelog