improve report

.github/workflows/run-benchmarks.yml

@@ -59,8 +59,7 @@ jobs:
           git checkout gh-pages
           git pull --rebase origin gh-pages
           mkdir -p benchmarks/reports
-          # create a dir with today and now in format yyyy-mm-dd HH:mm:ss
-          dir=benchmarks/reports/$(date +"%Y-%m-%d %H:%M:%S")
+          dir=benchmarks/reports/$(date +"%Y-%m-%d_%H-%M-%S")
           mkdir -p $dir
           cp /tmp/report.html $dir/report.html
           git commit -am "Update benchmarks ${{ github.run_id }} - $dir"