Markdown not supported in Options even when Slack allows them.

[nickovs]

In Slack's API, whether the Option object is allowed to take mrkdwn text or not depends the context. According to the documentation the text field of an Option is:

A text object that defines the text shown in the option on the menu. Overflow, select, and multi-select menus can only use plain_text objects, while radio buttons and checkboxes can use mrkdwn text objects. Maximum length for the text in this field is 75 characters.

Pre version 2.0, blockkit provided both MarkdownOption() and PlainOption() classes to properly support this. In the current code attempting Option().text(Text("*foo*: bar")) fails to build, no matter what context it is built in.

The current behaviour both makes blockkit>=2.0 incomplete in its support of Slack's API and is a regression from blockkit<2.0. It is also preventing me upgrading my app, since it uses mrkdwn formatting for a lot of checkboxes and radio buttons. It would be helpful if the full API was properly supported.

[nickovs]

Just for clarity, the failure to build is specifically due to a validation failure because the code disallows the otherwise legal option text structure. The exception raised is:

FieldValidationError: Field 'text': Only plain_text is allowed

This is raised even when built in the context of RadioButtons() or Checkboxes() options.