Update benchmark-action/github-action-benchmark action to v1.21.0 (#918)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/benchmark.yaml

@@ -62,7 +62,7 @@ jobs:
         run: nox -s benchmark
 
       - name: Store benchmark result in github.io
-        uses: benchmark-action/github-action-benchmark@4bdcce38c94cec68da58d012ac24b7b1155efe8b # v1.20.7
+        uses: benchmark-action/github-action-benchmark@a7bc2366eda11037936ea57d811a43b3418d3073 # v1.21.0
         with:
           name: Pytest-Benchmark Benchmark
           tool: "pytest"