[submodule] Update submodule dhcpmon to the latest HEAD automatically (#21818)

#### Why I did it
src/dhcpmon
```
* 2519a88 - (HEAD -> 202411, origin/202411) Merge pull request #34 from yaqiangz/202411_dhcpmon_bootp (2 days ago) [Kumaresh Perumal]
* 3e58f23 - Fix counting bootp packets by mistake (#31) (3 days ago) [Yaqiang Zhu]
```
#### How I did it
#### How to verify it
#### Description for the changelog

Author: mssonicbld