fix(ci): linting, permissions and configuration

.github/workflows/compress-images.yml

@@ -3,18 +3,15 @@
 # Open a Pull Request if any images can be compressed.
 name: Compress Images on Demand
 
-env:
-  ACTIONS_ALLOW_UNSECURE_COMMAND: false
-
 on:
   workflow_dispatch:
   schedule:
     - cron: "00 23 * * 0"
 
 permissions:
-  contents: write
-  statuses: write
-  pull-requests: write
+  contents: read
+  statuses: read
+  pull-requests: read
 
 jobs:
   CompressOnDemandOrSchedule: