[submodule] Update submodule sonic-utilities to the latest HEAD automatically (sonic-net#19522)

#### Why I did it
src/sonic-utilities
```
* b6f7c2b - (HEAD -> master, origin/master, origin/HEAD) [sfputil] Add loopback sub-command for debugging and module diagnosti… (sonic-net#3369) (27 hours ago) [Xinyu Lin]
* 1f94444 - Fix multi-asic behaviour for pg-drop (sonic-net#3058) (2 days ago) [bktsim]
* 789ef63 - Add Parallel option for apply-patch (sonic-net#3373) (3 days ago) [Xincun Li]
```
#### How I did it
#### How to verify it
#### Description for the changelog

Author: mssonicbld