feat: add workflow to release helm chart

[rasta-rocket]

Hi @cw-sakamoto 👋

First of all thanks a lot for this project, it is really useful 🤩 .

This little contribution allow us to release and download the helm chart in a more standard way compared to the usage of the helm plugin helm-git (also note that both method are compatible).

In order to the release process can work, we need to:

1. Create a git branch named gh-pages
2. Enable the github pages on the repo
3. Point the github pages to the branch gh-pages

As mentionned here

If you need more details, don't hesitate to ask

Cheers