CI: caching: rm schedule

It seems would not be needed.
`cabal.project` has pinned Hackage revision & when HLS code updates in `master`
is during merges.

Author: Anton-Latukha

.github/workflows/caching.yml

@@ -17,9 +17,6 @@ on:
   push:
     branches:
       - master
-  schedule:
-    # Try to save snapshot every day at 08:25 UTC (~00:25 in California)
-    - cron: "25 8 * * *"
 
 jobs:
   pre_job: