Configure Renovate (#4294)

* Add renovate.json

* Change renovate config file to be a dotfile

* Add "dependencies" label to Renovate PRs

* Disable Renovate for Ruby Bundler

This is already handled with Dependabot which is better integrated with
GitHub.

Co-authored-by: Renovate Bot <bot@renovateapp.com>
Co-authored-by: Matthew Haughton <3flex@users.noreply.github.com>

.renovaterc.json

@@ -0,0 +1,10 @@
+{
+  "labels": ["dependencies"],
+  "packageRules": [{
+    "matchManagers": ["bundler"],
+    "enabled": false
+  }],
+  "extends": [
+    "config:base"
+  ]
+}