feat: make k8s paths more flexible (#9)

This PR makes matching of k8s manifests more flexible.

Reviewed-on: #9
Reviewed-by: branch-buddy <branch-buddy@t00n.de>
Co-authored-by: Timo Behrendt <t.behrendt@t00n.de>
Co-committed-by: Timo Behrendt <t.behrendt@t00n.de>

k8s.json

@@ -2,7 +2,7 @@
   "$schema": "https://docs.renovatebot.com/renovate-schema.json",
   "kubernetes": {
     "enabled": true,
-    "managerFilePatterns": ["^k8s/*\\.yaml$"],
+    "managerFilePatterns": ["(^|/)k8s/.*\\.ya?ml$"],
     "labels": ["deps", "k8s"]
   }
 }