fix: run benchmark after publish to prevent workflow cancellation

Change benchmark trigger from release:published to workflow_run on
Publish so the two workflows no longer race. Benchmark now starts
only after Publish completes successfully.

Author: github-actions[bot]

.github/workflows/benchmark.yml

@@ -1,15 +1,19 @@
 name: Benchmark
 
 on:
-  release:
-    types: [published]
+  workflow_run:
+    workflows: ["Publish"]
+    types: [completed]
   workflow_dispatch:
 
 permissions: {}
 
 jobs:
   benchmark:
     runs-on: ubuntu-latest
+    if: >-
+      github.event_name == 'workflow_dispatch' ||
+      github.event.workflow_run.conclusion == 'success'
     permissions:
       contents: write
       pull-requests: write