Cannot chain attachments in builder when using MaildroidXAttachment list

[maximilian-schwaerzler]

Describe the bug
The function attachments(attachments: List<MaildroidXAttachment>) returns Unit instead of MaildroidX.Builder, making it not chainable.

To Reproduce
Use attachments(attachments: List<MaildroidXAttachment>) and use it in the MaildroidX.Builder.

Expected behavior
Replace the assignment to attachments(attachments: List<MaildroidXAttachment>) with a call to apply {...}