🔧(dependencies) update default renovate config

Update default Renovate configuration to open PRs on
the first day of each month instead of weekly.

Security updates remain handled immediately by Dependabot, while
Renovate manages regular dependency updates to keep the project
up to date with third-party packages.

renovate.json

@@ -3,6 +3,21 @@
   "dependencyDashboard": true,
   "labels": ["dependencies", "noChangeLog"],
   "packageRules": [
+    {
+        "groupName": "js dependencies",
+        "matchManagers": ["npm"],
+        "schedule": ["on the first day of the month"],
+        "matchPackagePatterns": ["*"],
+        "minimumReleaseAge": "7 days",
+        "internalChecksFilter": "strict"
+      },
+      {
+        "groupName": "python dependencies",
+        "matchManagers": ["setup-cfg", "pep621"],
+        "schedule": ["on the first day of the month"],
+        "matchPackagePatterns": ["*"],
+        "minimumReleaseAge": "7 days"
+      },
     {
       "enabled": false,
       "groupName": "ignored python dependencies",