[submodule] Update submodule sonic-stp to the latest HEAD automatically (sonic-net#23898)

#### Why I did it
src/sonic-stp
```
* e3626a4 - (HEAD -> master, origin/master, origin/HEAD) [MSTP] Fixing buffer OOB Read/Write issues (#72) (20 hours ago) [Shivashankar C R]
```
#### How I did it
#### How to verify it
#### Description for the changelog

Author: mssonicbld