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

…lly (#19325)

#### Why I did it
src/sonic-gnmi
```
* a610784 - (HEAD -> master, origin/master, origin/HEAD) Improve timeout for GNMI dbus service (#265) (3 days ago) [ganglv]
* b1c90c9 - Add unit test for vlan interface (#264) (6 days ago) [ganglv]
* fbf0234 - Add unit test for syslog config (#263) (6 days ago) [ganglv]
* 047fc29 - Add unit test for portchannel interface (#262) (6 days ago) [ganglv]
* 52dd8e7 - Add unit test for pg headroom (#261) (6 days ago) [ganglv]
* 8a10d9f - Add unit test for pfcwd status (#260) (6 days ago) [ganglv]
* 65a43bc - Add unit test for pfcwd interval (#259) (6 days ago) [ganglv]
* 0bbb9ef - Add unit test for ntp (#258) (7 days ago) [ganglv]
* e5c43a4 - Add unit test for monitor config (#257) (7 days ago) [ganglv]
* 8a8881e - Add unit test for mmu dynamic threshold (#256) (7 days ago) [ganglv]
* 76857df - Add unit test for lo interface (#255) (7 days ago) [ganglv]
* c35c69d - Add unit test for k8s config (#254) (8 days ago) [ganglv]
* dd0bdcf - Add unit test for IPV6 (#253) (8 days ago) [ganglv]
* 9a1133f - Add unit test for incremental qos (#252) (8 days ago) [ganglv]
* 9bf7969 - Add unit test for eth interface (#251) (8 days ago) [ganglv]
* 2e1eb05 - Add unit test for ECN config (#250) (8 days ago) [ganglv]
* 56f17eb - Add unit test for dynamic ACL (#249) (8 days ago) [ganglv]
* 388eba8 - Add unit test for DHCP relay (#245) (10 days ago) [ganglv]
* fd2fdf6 - Add unit test for CACL (#243) (11 days ago) [ganglv]
```
#### How I did it
#### How to verify it
#### Description for the changelog