create-self-hosted-runner: use better post-deployment script URL

We need to couple the post-deployment script URL more tightly to the
current revision, otherwise the workflow run might pick up an unintended
version of that script.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

.github/workflows/create-azure-self-hosted-runners.yml

@@ -36,7 +36,7 @@ env:
   ACTIONS_RUNNER_REPO: "${{ github.event.inputs.runner_repo || github.event.repository.name }}"
   DEALLOCATE_IMMEDIATELY: ${{ github.event.inputs.deallocate_immediately }}
   # This has to be a public URL that the VM can access after creation
-  POST_DEPLOYMENT_SCRIPT_URL: https://raw.githubusercontent.com/${{ github.repository }}/${{ github.ref_name }}/azure-self-hosted-runners/post-deployment-script.ps1
+  POST_DEPLOYMENT_SCRIPT_URL: https://raw.githubusercontent.com/${{ github.repository }}/${{ github.ref }}/azure-self-hosted-runners/post-deployment-script.ps1
   # Note that you'll need "p" (arm64 processor) and ideally "d" (local temp disk). The number 8 stands for 8 CPU-cores.
   # For a convenient overview of all arm64 VM types, see e.g. https://azureprice.net/?_cpuArchitecture=Arm64
   AZURE_VM_TYPE: Standard_D8plds_v5