This commit updates the Dokuwiki Docker image version in both
the Chart.yaml and values.yaml files from
`20250918-debian-12` to `20251031`.
The change was necessary to ensure users are running the latest
version of the Dokuwiki application, which may include important
security patches, bug fixes, and new features that enhance
overall stability and performance.
Additionally, the chart version has been updated to `1.2.1`
to reflect this change. No breaking changes are introduced with
this update, but users should test the new version to ensure
compatibility with their existing configurations.
