Change to ubuntu:latest and clean up

Author: sarahchen6

.github/workflows/ci.yml

@@ -7,9 +7,7 @@ on:
     branches:
       - master
   schedule:
-    # Tuesday at 10. One day after the CircleCI scheduled upddate
-    # See: https://github.com/CircleCI-Public/cimg-base/blob/main/.circleci/schedule.json
-    - cron: '0 10 * * 2' 
+    - cron: '0 0 * * 0' 
   workflow_dispatch:
 
 jobs: