[submodule] Update submodule sonic-swss to the latest HEAD automatica…

…lly (#18777)

#### Why I did it
src/sonic-swss
```
* a821af04 - (HEAD -> 202311, origin/202311) [ACL] Remove flex counter when updating ACL rule (#3118) (3 days ago) [bingwang-ms]
```
#### How I did it
#### How to verify it
#### Description for the changelog