Fix cron schedule to run past minute 0 every 2nd hour

In the previous schedule, we were running at every minute at every 2nd hour.

PiperOrigin-RevId: 698804124

Author: nitins17

.github/workflows/cloud-tpu-ci-nightly.yml

@@ -13,7 +13,7 @@
 name: CI - Cloud TPU (nightly)
 on:
   schedule:
-    - cron: "* */2 * * *" # Run every 2 hours
+    - cron: "0 */2 * * *" # Run every 2 hours
   workflow_dispatch: # allows triggering the workflow run manually
 # This should also be set to read-only in the project settings, but it's nice to
 # document and enforce the permissions here.