Auto merge of rust-lang#3262 - saethlin:tier-2-cron, r=saethlin

Run the tier 2 sysroots job on a schedule, not push

I had this running on push instead of on a schedule so that I could verify that it worked, then forgot to switch it back to cron before merging.

Author: bors

src/tools/miri/.github/workflows/sysroots.yml

@@ -1,8 +1,8 @@
 name: Tier 2 sysroots
 
-on: push
-#  schedule:
-#    - cron: '44 4 * * *' # At 4:44 UTC every day.
+on:
+  schedule:
+    - cron: '44 4 * * *' # At 4:44 UTC every day.
 
 defaults:
   run: