Harden sleep-test workflow permissions and pin checkout

Author: Goryudyuma

.github/workflows/sleep-test.yml

@@ -5,10 +5,14 @@ on:
 jobs:
   long-sleep:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
     timeout-minutes: 20
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5
+        with:
+          persist-credentials: false
       - name: Start Workflow Telemetry
         uses: ./
       - name: Sleep for 10 minutes