[submodule] Update submodule sonic-stp to the latest HEAD automatically (#24654)

#### Why I did it
src/sonic-stp
```
* 6be3721 - (HEAD -> master, origin/master, origin/HEAD) Correcting stp-stpmgrd IPC data structure similar to structure defined in stpmgr.h file (#80) (4 days ago) [Divya Kumaran Chandralekha]
* e80c7be - [stpctl] stpctl enhancements for mstp debugging commands (#79) (5 days ago) [vganesan-nokia]
* bfcb492 - [mstp] Fix for port enable handlinging and rx pkt type check (#78) (5 days ago) [vganesan-nokia]
```
#### How I did it
#### How to verify it
#### Description for the changelog

Author: mssonicbld