Move nightly builds to 11pm PT (facebookresearch#3737)

Summary:
Pull Request resolved: facebookresearch#3737

This moves nightly builds away from when most of the team is working to avoid exhausting limited resources like custom hardware / specialized hardware.

Reviewed By: bshethmeta

Differential Revision: D60976671

fbshipit-source-id: 1a8521379654a06a793fda0ae3f3bd1bf6fa8bf6

Author: ramilbakhshyiev

.github/workflows/nightly.yml

@@ -1,7 +1,7 @@
 name: Nightly
 on:
   schedule:
-    - cron:  '10 1 * * *'
+    - cron:  '10 6 * * *'
 env:
   OMP_NUM_THREADS: '10'
   MKL_THREADING_LAYER: GNU