fix: prevent duplicate auth header in GitHub Actions workflow (#7091)

.github/workflows/update-directorymd.yml

@@ -1,4 +1,4 @@
-name: Generate Directory Markdown
+name: Generate Directory Markdown
 
 on:
   push:
@@ -15,6 +15,8 @@ jobs:
     steps:
       - name: Checkout Repository
         uses: actions/checkout@v6
+        with:
+          persist-credentials: false
 
       - name: Run Directory Tree Generator
         uses: DenizAltunkapan/directory-tree-generator@v2