fix: dont start multiple builders (#6437)

Something happened here recently. Have to look into why multiple
builders might be starting, but most likely this was just hit at the
same time

.github/workflows/setup-runner.yml

@@ -28,6 +28,8 @@ on:
       DOCKERHUB_PASSWORD:
         required: true
 
+concurrency:
+  group: ci-${{ inputs.username }}-${{ inputs.runner_type }}-${{ inputs.runner_action }}
 env:
   DOCKERHUB_PASSWORD: "${{ secrets.DOCKERHUB_PASSWORD }}"
   RUN_ID: ${{ github.run_id }}
@@ -79,4 +81,4 @@ jobs:
         uses: ./.github/ensure-builder
         with:
           runner_action: ${{ inputs.runner_action }}
-          runner_type: ${{ inputs.runner_type }}
+          runner_type: ${{ inputs.runner_type }}