Reduce link validator schedule (#3430)

Author: ennru

.github/workflows/link-validator.yml

@@ -9,7 +9,7 @@ on:
       - v*
   workflow_dispatch:
   schedule:
-    - cron:  '0 6 * * 1'
+    - cron:  '0 6 1 * *'
 
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   contents: read