.github/workflows: Change adi-kuiper-gen branch

Signed-off-by: Ioana Risteiu <Ioana.Risteiu@analog.com>

Author: iristeiu06

.github/workflows/gmsl-kernel-build.yml

@@ -138,6 +138,6 @@ jobs:
             "client_payload": {
               "run_id": "${{ github.run_id }}",
               "sha": "${{ github.sha }}",
-              "branch": "${{ github.ref_name }}"
+              "branch": "gmsl-rpi-6.13.y"
             }
           }'