Update Renovate config (#147)

Why these changes are being introduced:
* Simplify configuration options to only include setting/default
overrides and add vulnerability alerts.

How this addresses that need:
* Update lockFileMaintenance to override 'enabled' and 'schedule'
* Add vulnerabilityAlerts to override 'label'

Side effects of this change:
* None

Relevant ticket(s):
* None

Author: jonavellecuerdo

renovate.json

@@ -10,18 +10,13 @@
   ],
   "lockFileMaintenance": {
     "enabled": true,
-    "recreateWhen": "always",
-    "rebaseStalePrs": true,
-    "branchTopic": "lock-file-maintenance",
-    "commitMessageAction": "Lock file maintenance",
-    "commitMessageTopic": null,
-    "commitMessageExtra": null,
     "schedule": [
       "* 4 * * 1"
-    ],
-    "groupName": null,
-    "prBodyDefinitions": {
-      "Change": "All locks refreshed"
-    }
+    ]
+  },
+  "vulnerabilityAlerts": {
+    "labels": [
+      "security"
+    ]
   }
 }