fix(ci): add permissions to file size check workflow

Resolves 'Resource not accessible by integration' error.
Adds read permissions for contents and pull-requests.

.github/workflows/check-filesize.yml

@@ -5,6 +5,10 @@ on:
     branches: [main]
   workflow_dispatch:
 
+permissions:
+  contents: read
+  pull-requests: read
+
 jobs:
   check-size:
     runs-on: ubuntu-latest