Update official Helm Chart as part of deployment process

[gabrielgrant]

The official Helm repo now contains a (mostly-working) Chart for Pachyderm (tracked in #1068)

Currently the version requires manual updating. We should do so as part of our release process (probably first by just documenting that the releaser needs to submit a PR manually, and later by automatically opening that PR). I believe all that needs to be changed with each release is updating the image version numbers, chart version number, and app version number

[jeanlucmongrain]

it had been updated end of March, is this still a problem?

[gabrielgrant]

The issue is that every time we do a deploy, someone needs to manually update the chart. So far @jonandernovella has been fairly diligent in doing so (and it does appear to be up to date with v1.7.3 at the moment -- thanks @jonandernovella !), but we should really be able to automate this, to save him from having to do so

[pappasilenus]

@chainlink another user request here: https://pachyderm-users.slack.com/archives/C3UN0S0Q0/p1573371568479800