Use tag pr-xyz for triton-benchmarks runs on PRs.

If triton-benchmarks is triggered by PR then it gets tagged by `pr-xyz`
where `xyz` is the PR number.

Author: pbchekin

.github/workflows/triton-benchmarks.yml

@@ -48,7 +48,7 @@ env:
   PYTHON_VERSION: "3.10"
   BENCHMARKING_METHOD: ${{ inputs.benchmarking_method || 'PYTORCH_LEGACY_PROFILER_USING_IPEX' }}
   USE_IPEX: ${{ github.event_name != 'workflow_dispatch' && '1' || inputs.benchmarking_method  == 'PYTORCH_LEGACY_PROFILER_USING_IPEX' && '1' || '0' }}
-  TAG: ${{ inputs.tag || (github.event_name == 'pull_request' && 'pr') || (github.event_name == 'schedule' && 'ci') || 'test' }}
+  TAG: ${{ inputs.tag || (github.event_name == 'pull_request' && format('pr-{0}', github.event.number) || (github.event_name == 'schedule' && 'ci') || 'test' }}
 
 jobs:
   build: