Bump paperless-ngx version to 0.25.7 and update probes

Updated the paperless-ngx Helm chart to version 0.25.7 from
0.25.6 to incorporate the latest features and fixes. The appVersion
remains at 2.20.0.

Additionally, modified the liveness and readiness probes
configuration in the values.yaml file to nest probe options
under the spec field, aligning with best practices for Helm charts.
These changes normalize the probe specifications, ensuring better
compatibility and clarity for users managing their Kubernetes
deployments. No breaking changes were introduced in these updates.

charts/paperless-ngx/README.md

@@ -2,7 +2,7 @@
 
 <img src="https://raw.githubusercontent.com/paperless-ngx/paperless-ngx/b948750/src-ui/src/assets/logo-notext.svg" align="right" width="92" alt="paperless-ngx logo">
 
-![Version: 0.25.6](https://img.shields.io/badge/Version-0.25.6-informational?style=flat)
+![Version: 0.25.7](https://img.shields.io/badge/Version-0.25.7-informational?style=flat)
 ![Type: application](https://img.shields.io/badge/Type-application-informational?style=flat)
 ![AppVersion: 2.20.0](https://img.shields.io/badge/AppVersion-2.20.0-informational?style=flat)