Feature: Add test for enabling redis to ci

[jessebot]

Description of the change

I'd like to add an isolated redis test to our CI to ensure this chart works properly with redis. It would go somewhere in here: https://github.com/nextcloud/helm/blob/bf6cc4a9df0b3bffd3915dc940ddbec71976429e/.github/workflows/lint-test.yaml#L69-L83

Benefits

Ensure this chart works properly with redis, and will also make sure we catch breaking changes in the bitnami chart, if they happen.

Possible drawbacks

Another test to maintain. 😅