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

…lly (sonic-net#19325)

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