ci: PR-number concurrency keying on the eval and Windows lanes too

Same fork-branch-name collision as free-tests.yml: bare head_ref
carries no owner prefix, so same-name branches from different forks
shared a cancel-in-progress group.

.github/workflows/evals.yml

@@ -5,7 +5,7 @@ on:
   workflow_dispatch:
 
 concurrency:
-  group: evals-${{ github.head_ref || github.run_id }}
+  group: evals-${{ github.event.pull_request.number || github.run_id }}
   cancel-in-progress: true
 
 env:

.github/workflows/windows-free-tests.yml

@@ -28,7 +28,7 @@ on:
   workflow_dispatch:
 
 concurrency:
-  group: windows-free-${{ github.head_ref || github.run_id }}
+  group: windows-free-${{ github.event.pull_request.number || github.run_id }}
   cancel-in-progress: true
 
 jobs: