chore(automation): update spec-update.yml cron schedule (#34840)

### Reason for this change

Updating L1 spec automation cron schedule
`37 13 * * 1` -> `15 10 * * 1`

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Author: kumvprat

.github/workflows/spec-update.yml

@@ -2,8 +2,8 @@ name: AWS Service Spec Update
 
 on:
   schedule:
-    # Every Monday at 13:37 UTC
-    - cron: 37 13 * * 1
+    # Every Monday at 10:15 UTC since dependency releases are on Fridays : https://github.com/cdklabs/awscdk-service-spec/releases?q=-spec&expanded=true
+    - cron: 15 10 * * 1
   workflow_dispatch: {}
 
 jobs: