Fix CODEOWNERS trailing newline and add workflow permissions

Add missing trailing newline to .github/CODEOWNERS and set
permissions: read-all on the codeowners workflow for least-privilege.

Author: Nissan Pow

.github/CODEOWNERS

@@ -80,4 +80,4 @@
 # Rule extracted from metaflow/plugins/uv/CODEOWNERS
 /metaflow/plugins/uv/**/* @saikonen
 
-#################################### Generated content - do not edit! ####################################
+#################################### Generated content - do not edit! ####################################

.github/workflows/codeowners.yml

@@ -6,6 +6,8 @@ on:
       - '**/CODEOWNERS'
       - '.codeowners-generatorrc'
 
+permissions: read-all
+
 jobs:
   check-codeowners:
     runs-on: ubuntu-latest