Replace Dependabot with Renovate

Author: uhafner

.github/dependabot.yml

@@ -0,0 +1,6 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": ["github>jenkinsci/renovate-config"],
+  "commitMessageAction": "Bump",
+  "ignorePaths": ["src/**"]
+}