chore: Sync common workflows

This is an automated sync of common workflows for this organization.
The upstream source is:
shaka-project/shaka-github-tools@be928d3

Author: shaka-bot

.github/workflows/sync-labels.yaml

@@ -26,6 +26,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           repository: shaka-project/shaka-github-tools
+          persist-credentials: false
 
       # TODO: revert to micnncim and new release after landing
       #       https://github.com/micnncim/action-label-syncer/pull/68

.github/workflows/update-issues.yaml

@@ -23,6 +23,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           repository: shaka-project/shaka-github-tools
+          persist-credentials: false
 
       - name: Update Issues
         env: