[sonic-snmpagent] Update submodule (#10736)

Includes below commits
```
1477c36 2022-05-04 | Fix: if routestr does not exist, skip (#257) [Qi Luo]
5c08435 2022-05-04 | Add VoQ Recirc interface (i.e., Ethernet-Rec) to interface maps for S… (#244) [Song Yuan]
57f1af6 2022-05-02 | Fix: not to use blocking get_all() after keys() (#255) [Qi Luo]
33fdf9d 2022-04-06 | [RFC2737, RFC3433] Exclude RJ45 port from Entity MIB and Entity sensor MIB (#247) [Kebo Liu]
```