Support DaskExecutor

[torse]

Checks

• I have checked for existing issues.
• This report is about the User-Community Airflow Helm Chart.

Motivation

I would like to use the DaskExecutor to offload task execution to our Dask cluster as documented here: https://airflow.apache.org/docs/apache-airflow/stable/executor/dask.html. Therefore I've updated my values.yaml like this:

airflow:
  executor: DaskExecutor
  config:
    AIRFLOW__DASK__CLUSTER_ADDRESS: "dask-scheduler:8786"

However, the DaskExecutor seems to be unsupported by the chart as the following error is thrown when upgrading:

helm upgrade --install --cleanup-on-fail airflow airflow-stable/airflow -f /local/.../values-airflow.yml
Error: UPGRADE FAILED: execution error at (airflow/templates/_helpers/validate-values.tpl:29:5): The `airflow.executor` must be one of: [CeleryExecutor, CeleryKubernetesExecutor, KubernetesExecutor]!

Implementation

No response

Are you willing & able to help?

• I am able to submit a PR!
• I can help test the feature!