chore: Add dependency dashboard

Example: clap-rs/clap#4824

I'm hoping this will make it easier to see what is going on with
problems with RenovateBot, like our MSRVs not updating atm (#13254).

Author: epage

Diff for: .github/renovate.json5

@@ -4,7 +4,7 @@
   ],
   semanticCommits: 'enabled',
   configMigration: true,
-  dependencyDashboard: false,
+  dependencyDashboard: true,
   ignorePaths: [
     '**/tests/**',
   ],