[submodule] Update submodule sonic-gnmi to the latest HEAD automatically (#16480)

#### Why I did it
src/sonic-gnmi
```
* 6fd461c - (HEAD -> master, origin/master, origin/HEAD) Get origin from prefix (#149) (17 hours ago) [ganglv]
```
#### How I did it
#### How to verify it
#### Description for the changelog
This commit is contained in:
mssonicbld 2023-09-07 18:34:19 +08:00 committed by GitHub
parent e22136dd9f
commit 92d20cc9a3
No known key found for this signature in database
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@ -1 +1 @@
Subproject commit 7a1b7cd99105cf1e183e8de03cbeb80a942a60af
Subproject commit 6fd461ca396d39ffc677a5b06370e84d73e30f54