ci(benchmarks): reduce frequency from weekly to monthly (#391)

Author: Fdawgs

.github/workflows/benchmarks.yml

@@ -7,7 +7,7 @@ on:
       - main
   schedule:
     # * is a special character in YAML so you have to quote this string
-    - cron:  '0 0 * * 1'
+    - cron:  '0 0 1 * *'
 
 # This allows a subsequently queued workflow run to interrupt previous runs
 concurrency: