Update mariadb helm chart to 20.0.0 / breaking changes #658

Description of the change

Update the chart dependency of mariadb to 20.0.0.

Benefits

The 20.0.0-chart uses mariadb 11.4 which is supported by nextcloud (https://docs.nextcloud.com/server/latest/admin_manual/installation/system_requirements.html). The current dependency uses mariadb 11.3. I think it is usually a good idea to do the minor release upgrades for mariadb one after another.

The helm chart v19 also upgraded to mariadb 11.4, but documented no breaking changes.

The currently used container images do have some critical and high security vulnerabilites. So it is probably also a good idea to go to a newer container image.

Possible drawbacks

The v20 chart has a breaking change. Upgrading needs a workaround that is documented by bitnami: https://github.com/bitnami/charts/tree/main/bitnami/mariadb

Additional information

Because of the breaking change it is probably a good idea to also update the redis dependency to 20.3.0. This will upgrade redis from 7.2.x to 7.4.x. I see no breaking changes in the release notes and my other redis instances upgraded smoothly with the same chart.

7.4.x contains some security fixes.

https://github.com/bitnami/charts/tree/main/bitnami/redis

Probably it is the same with the postgresql dependency, but I do not deploy postgresql with bitnami charts, so I have no experience on that upgrade. It would be a major upgrade which also needs manual intervention with postgresql.