Implementation of CI/CD to automate deployments

[NathaelB]

Specs

For the moment, it's a good idea to do continuous integration when a PullRequest is open, checking that the code flows and that the tests pass.

This will avoid sources of error during reviews by letting certain code through.

In addition, as soon as a push is made to main, a workflow can be launched for:

• lint / tests
• update chart helm (with the commit sha)
• push to git
• build & push on `ghcr.io

[NathaelB]

There are two workflows on the main branch to meet requirements.

It would be interesting to add new workflows for deployment in other environments, such as production or staging, using tags and github releases.