Clean up comments in periodic_tests.yml

Author: MatthewMiddlehurst

.github/workflows/periodic_tests.yml

@@ -70,9 +70,6 @@ jobs:
           python_version: "3.12"
           restore_cache: "false"
 
-      # Install only the binder extra so this job matches the environment
-      # notebooks actually run in on binder (see .binder/Dockerfile). Using
-      # all_extras here hides missing binder dependencies.
       - name: Install dependencies
         uses: nick-fields/retry@v4
         with: