Add explicit permissions block to testflight.yml

Author: BYK

.github/workflows/testflight.yml

@@ -9,6 +9,10 @@ on:
       - '.github/workflows/testflight.yml'
   workflow_dispatch:
 
+permissions:
+  contents: write
+  pull-requests: write
+
 jobs:
   upload_to_testflight:
     name: Build and Upload to Testflight