Run CI at midnight Pacific

Many Cypress Windows tests are timing out even after increasing
the timeout to 2 hours, likely due to
actions/runner-images#7320. Hopefully
running the tests at night during reduced load will reduce the
prevalence of noisy neighbors since the GitHub Windows runners
seem unable to properly isolate compute-heavy workloads.

.github/workflows/ci.yaml

@@ -8,8 +8,8 @@ on:
 
   # Run the pipeline daily so that we get continuous dogfooding.
   schedule:
-    # Run at 6pm UTC/10am Pacific
-    - cron: 0 18 * * *
+    # Run at 8am UTC/midnight Pacific
+    - cron: 0 8 * * *
 
   # Allows you to run this workflow manually from the Actions tab
   workflow_dispatch: {}