Add explicit permissions to pr.yml workflow

Co-authored-by: jonrohan <[email protected]>

Author: Copilot

.github/workflows/pr.yml

@@ -12,6 +12,8 @@ name: Build and run tests
 jobs:
   test:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
     steps:
       - uses: actions/checkout@v4
       - name: Install dependencies