Make test-yaml executed with only read permissions.

Signed-off-by: Kurt Garloff <[email protected]>

Author: garloff

.github/workflows/test-yaml.yml

@@ -9,6 +9,8 @@ on:
 
 jobs:
   default:
+    permissions:
+      contents: read
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v3