[submodule] Update submodule sonic-ztp to the latest HEAD automatical…

…ly (sonic-net#18097)

#### Why I did it
src/sonic-ztp
```
* 56cebae - (HEAD -> master, origin/master, origin/HEAD) Enhancements to allow custom umask usage while executing plugins (#42) (2 hours ago) [rajendra-dendukuri]
```
#### How I did it
#### How to verify it
#### Description for the changelog