Fix release workflow to use correct build number

Author: philwebb

.github/workflows/release.yml

@@ -48,11 +48,12 @@ jobs:
       run: git push origin HEAD --tags
     outputs:
       release-version: ${{ steps.deduce-versions.outputs.release-version }}
+      release-build-number: ${{ github.run_number }}
   promote:
     name: Promote
     needs: stage
     uses: ./.github/workflows/promote.yml
     with:
       environment: ${{ inputs.environment }}
       version: ${{needs.stage.outputs.release-version}}
-      build-number: ${{ github.run_number }}
+      build-number: ${{ needs.stage.outputs.release-build-number }}