Change previous branch in MN upgrade action

Author: Alex-Welsh

.github/workflows/stackhpc-multinode.yml

@@ -71,6 +71,6 @@ jobs:
       ssh_key: ${{ inputs.ssh_key }}
       stackhpc_kayobe_config_version: ${{ github.ref_name }}
       # NOTE(upgrade): Reference the PREVIOUS release here.
-      stackhpc_kayobe_config_previous_version: stackhpc/2023.1
+      stackhpc_kayobe_config_previous_version: rabbitmq-multiple-versions
       terraform_kayobe_multinode_version: ${{ inputs.terraform_kayobe_multinode_version }}
     secrets: inherit