[submodule] Update submodule sonic-snmpagent to the latest HEAD automatically (#20504)

#### Why I did it
src/sonic-snmpagent
```
* c5301b2 - (HEAD -> master, origin/master, origin/HEAD) Fix SNMP output having fewer unicast queues than expected (#330) (23 hours ago) [Justin Wong]
```
#### How I did it
#### How to verify it
#### Description for the changelog

Author: mssonicbld