[submodule] Update submodule sonic-gnmi to the latest HEAD automatically (#16024)

#### Why I did it
src/sonic-gnmi
```
* c548cc2 - (HEAD -> master, origin/master, origin/HEAD) Support empty protobytes (#141) (2 hours ago) [ganglv]
```
#### How I did it
#### How to verify it
#### Description for the changelog
This commit is contained in:
mssonicbld 2023-08-03 16:32:37 +08:00 committed by GitHub
parent 13f081e926
commit 9cc2b2badd
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23

@ -1 +1 @@
Subproject commit 58a7b20b760561dd4d1156e1e91d7addc434dc39
Subproject commit c548cc2088625c6a2ec3d4bea7f41a080f25cb0e