🖌️ renovate: limit System.CommandLine updates to once per month

Author: database64128

renovate.json

@@ -2,5 +2,11 @@
     "$schema": "https://docs.renovatebot.com/renovate-schema.json",
     "extends": [
         "github>database64128/renovate-config:dotnet"
+    ],
+    "packageRules": [
+        {
+            "matchPackageNames": ["System.CommandLine"],
+            "schedule": ["monthly"]
+        }
     ]
 }