[submodule] Update submodule sonic-snmpagent to the latest HEAD automatically (#16832)

#### Why I did it
src/sonic-snmpagent
```
* 77e9374 - (HEAD -> 202012, origin/202012) Fix backup port rfc2863 UT to 202012 branch issue (#298) (12 hours ago) [Hua Liu]
* 2cb8241 - Add ifhighspeed UT (#296) (3 days ago) [Hua Liu]
```
This commit is contained in:
mssonicbld 2023-10-14 08:43:37 +08:00 committed by GitHub
parent 3b0fb656ca
commit 1ff84b2273
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@ -1 +1 @@
Subproject commit 64f0def9275f6bc6275f51093ba641fb140178e8
Subproject commit 77e93742ef35cfad0d0ceeacd73db25d19c86379