Write benchmark results to the job summary

Co-authored-by: Miles Cranmer <miles.cranmer@gmail.com>

Author: MilesCranmerBot

.github/workflows/benchmark_pr.yml

@@ -10,3 +10,4 @@ jobs:
         with:
           tune: "true"
           bench-on: ${{ github.event.pull_request.head.sha }}
+          job-summary: "true"