Add explicit permissions block to leaderboard workflow

Agent-Logs-Url: https://github.com/NextCommunity/NextCommunity.github.io/sessions/aa529b1f-6c33-47b9-854e-af24ac43a895

Co-authored-by: jbampton <418747+jbampton@users.noreply.github.com>

Author: Copilot

.github/workflows/leaderboard.yml

@@ -5,6 +5,9 @@ on:
     - cron: "0 0 * * *" # every day at midnight UTC
   workflow_dispatch: # allow manual runs
 
+permissions:
+  contents: read
+
 jobs:
   leaderboard:
     if: github.repository == 'NextCommunity/NextCommunity.github.io'