Enable a daily run of the CI

Recently, changes to ceph nautilus reminded me that due to the low rate of PRs we don't always catch things that change in our dependencies right away. I propose adding a daily CI run that help catch these kind of things sooner and can help distinguish between a PR related failure and random flakiness and upstream changes.

.github/workflows/main.yml

@@ -8,6 +8,8 @@ on:
     branches: [ master ]
   pull_request:
     branches: [ master ]
+  schedule:
+    - cron: 1 1 * * *
 
 jobs:
   # Run static/code-quality checks