[submodule] Update submodule sonic-snmpagent to the latest HEAD automatically (#17824)

#### Why I did it
src/sonic-snmpagent
```
* 4a6de8b - (HEAD -> master, origin/master, origin/HEAD) Set the execute bit on sysDescr_pass.py (#306) (6 hours ago) [Andre Kostur]
```
#### How I did it
#### How to verify it
#### Description for the changelog
This commit is contained in:
mssonicbld 2024-01-18 14:35:59 +08:00 committed by GitHub
parent d9517c77f1
commit 07a43b96b7
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@ -1 +1 @@
Subproject commit 29481f9c42c53123a88baa8a6e64cf8a4e37041f Subproject commit 4a6de8b936a50fd8b3ea6a3b9931b9c6a03b4c18