Addons: function "required" not defined

[judge-red]

What happened:

The addons use a function called required to check whether required parameters/credentials are provided. However, this function doesn't seemto be working as intended:

time="09:48:41 UTC" level=warning msg="Task failed, error was: failed to load and apply the addon \"backups-restic\": failed to load and apply embedded addon: failed to template addons manifest backups-restic.yaml: template: addons-base:8: function \"required\" not defined"

What is the expected behavior:

I should see the string provided to the required function rather than the error above.

How to reproduce the issue:
Specify an embedded addon that requires some parameter or credential without providing them. For example try to install the backups-restic addon without specifying any parameters.

Anything else we need to know?

The required function was added in #1618 as a fix for #1555.

Information about the environment:
KubeOne version (kubeone version): 1.3.3
Operating system: alpine:3.15.0
Provider you're deploying cluster on: OpenStack
Operating system you're deploying on: Flatcar

[kron4eg]

@judge-red it was fixed in #1737