[submodule][202311] Update submodule sonic-gnmi to the latest HEAD automatically

[mssonicbld]

Why I did it

src/sonic-gnmi

* 12f436b - (HEAD -> 202311, origin/202311) Merge pull request #440 from liuh-80/dev/liuh/multirole_202311_cp (22 hours ago) [Ying Xie]
* 94bbdd1 - Update server_test.go (2 weeks ago) [Hua Liu]
* 4fbb981 - Update server_test.go (2 weeks ago) [Hua Liu]
* 342d6c0 - Update clientCertAuth.go (2 weeks ago) [Hua Liu]
* b7f999c - Update azure-pipelines.yml (2 weeks ago) [Hua Liu]
* a2bb467 - Update azure-pipelines.yml (2 weeks ago) [Hua Liu]
* 08f78b7 - Update azure-pipelines.yml (2 weeks ago) [Hua Liu]
* def33cc - Add cert multiple roles support (#366) (2 weeks ago) [Hua Liu]

How I did it

How to verify it

Description for the changelog

[mssonicbld]

/azp run Azure.sonic-buildimage

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).