feat: add private helm repo support (#6)

Adding support for our private helm repository enabling updates of private resources.

Reviewed-on: #6
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>

helm.json

@@ -13,5 +13,13 @@
   "helmfile": {
     "enabled": true,
     "addLabels": ["deps", "helm"]
-  }
+  },
+  "hostRules": [
+    {
+      "matchHost": "gitea.t000-n.de",
+      "hostType": "helm",
+      "username": "{{ secrets.HELM_REGISTRY_USER }}",
+      "password": "{{ secrets.HELM_REGISTRY_PASSWORD }}"
+    }
+  ]
 }