build: enable renovate dependency dashboard

Enable the Renovate dashboard to see what we are missing/what
is going on after switching to the self-hosted runner. Renovate
might avoid some PRs due to previously-closed old PRs with
the official Mend renovate app operating on upstream branches.

Also provide the Renovate schema.

Author: devversion

renovate.json

@@ -1,13 +1,15 @@
 {
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
   "rangeStrategy": "replace",
   "semanticCommits": "enabled",
   "semanticCommitType": "build",
-  "semanticCommitScope": null,
+  "semanticCommitScope": "",
   "separateMajorMinor": false,
   "prHourlyLimit": 2,
   "labels": ["target: minor", "action: merge"],
   "timezone": "America/Tijuana",
   "lockFileMaintenance": { "enabled": true },
+  "dependencyDashboard": true,
   "schedule": ["after 10:00pm every weekday", "before 4:00am every weekday", "every weekend"],
   "baseBranches": ["main"],
   "ignoreDeps": ["@types/node", "quicktype-core"],