[submodule] Update submodule sonic-stp to the latest HEAD automatically (sonic-net#24533)

#### Why I did it
src/sonic-stp
```
* d30e086 - (HEAD -> master, origin/master, origin/HEAD) Fix issues with PDU structure alignment, IPC msg processing (sonic-net#73) (4 days ago) [Yogapriya-cisco]
```
#### How I did it
#### How to verify it
#### Description for the changelog

Signed-off-by: Feng Pan <[email protected]>

Author: mssonicbld