[submodule] Update submodule sonic-dash-api to the latest HEAD automa…

…tically (sonic-net#19872)

#### Why I did it
src/sonic-dash-api
```
* 39e4a63 - (HEAD -> master, origin/master, origin/HEAD) Add privatelink underlay_sip field for route table (#25) (24 hours ago) [Lawrence Lee]
```
#### How I did it
#### How to verify it
#### Description for the changelog