fix: ref main in reusable PR review workflows (#3326)

Author: laurakwhit

.github/workflows/pr-review-notification.yml

@@ -27,7 +27,7 @@ jobs:
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           repository: temporalio/ui
-          ref: ${{ github.workflow_sha }}
+          ref: main
           path: ._reusable
 
       - name: Get Reviewers to Notify

.github/workflows/pr-review-reminder.yml

@@ -32,7 +32,7 @@ jobs:
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           repository: temporalio/ui
-          ref: ${{ github.workflow_sha }}
+          ref: main
           path: ._reusable
 
       - name: Find Pending Reviews and Send Reminders