[submodule][202012]: Update submodule pointer for snmpagent (#6954)

183162f Fix issue: expect redis pubsub data to be str type instead of bytes type (#196)

#### Why I did it

Update submoduel for snmpagent for 202012 branch since there is not 202012 branch for snmpagent

#### How I did it

Update submodule pointer

#### How to verify it

Run build