docs: update references to bfra-me/renovate-config to v3

| datasource  | package                 | from    | to     |
| ----------- | ----------------------- | ------- | ------ |
| github-tags | bfra-me/renovate-config | v2.11.0 | v3.1.2 |

README.md

@@ -15,7 +15,7 @@ This repository contains [Renovate](https://renovatebot.com/) configuration pres
 
 ```json
 {
-  "extends": ["github>bfra-me/renovate-config#v2.11.0"]
+  "extends": ["github>bfra-me/renovate-config#v3.1.2"]
 }
 ```