use autoscaling/v2 in hpa

[seanrmurphy]

I'm checking hpa config across our resources as there are changes to what is supported in k8s 1.25.

Most of our hpas have logic to support different api versions generally and there is a tendency to move to autoscaling/v2 generally - it would be good to support that in this hpa.

See here for example:
https://github.com/SwissDataScienceCenter/renku-notebooks/blob/master/helm-chart/renku-notebooks/templates/hpa.yaml#L3