fix(helm): specify new stable repo for helm v2.16.3

[davious]

The repository that helm v2.16.3 uses is now depreciated, moved to https://charts.helm.sh/stable

in deps.sh, helm init crashes unless the new stable repo location is specifically set, otherwise the error below is seen

Error: error initializing:
Looks like "https://kubernetes-charts.storage.googleapis.com"
is not a valid chart repository or cannot be reached:
Failed to fetch https://kubernetes-charts.storage.googleapis.com/index.yaml : 403 Forbidden

see https://stackoverflow.com/questions/65407317/helm-init-failed-is-not-a-valid-chart-repository-or-cannot-be-reached-failed-to

[davious]

heh, closing in deference to #56 or $59