Update version to 0.7.0 and add RAG service configuration

This commit updates the version of the Paperless AI Helm Chart
from 0.6.0 to 0.7.0, reflecting new changes and improvements in
the software.

Additionally, two new environment variables have been added
to the values.yaml file:
- `RAG_SERVICE_URL`, which sets the URL for the RAG service,
  defaulting to http://localhost:8000.
- `RAG_SERVICE_ENABLED`, a boolean flag to enable or disable the
  RAG service, set to true by default.

These changes are necessary to incorporate the RAG service in
the deployment configuration, enhancing the functionality
of Paperless AI. No breaking changes are introduced with this
update.

charts/paperless-ai/Chart.yaml

@@ -1,7 +1,7 @@
 apiVersion: v2
 name: paperless-ai
 description: Ein Helm Chart für Paperless AI, basierend auf der Docker Compose Konfiguration.
-version: 0.6.0
+version: 0.7.0
 appVersion: 3.0.7
 keywords:
   - paperless-ai