Keep Chart.appVersion in sync with langfuse releases and track them automatically

[frittentheke]

First of all, thanks for providing and maintaining this Helm chart!

I would be nice if the Helm chart was automatically tracking the latest (stable) release of langfuse via bumps to the appVersion.
Currently it seems to use a major appVersion of "2" .
while this is nice to always start with most recent version 2.x.y, this is not as explicit as one would like.
Event though you have the imagePullPolicy set to always, this requires the recreation of the Pod which then does not happen explicitly via a helm upgrade but co-incidentally with other K8s cluster operations.

I'd rather just use the Helm chart version as the "package version" and as an indicator that there is an update available.