@@modeleditor is missing its styling in Version 4.0.0

[Nimo-19]

Issue description

After I updated to Version 4.0.0 I noticed the xml modeleditor is missing its styling.

Steps to reproduce the issue

1. Install minimal plone 5.2.8 buildout and add easyform
2. Create a form
3. Choose the action 'define form actions'
4. Click the "Edit XML Actions Model" Button

What's the expected result?

• The Text Field containing the xml data has syntax highlighting

What's the actual result?

• A unstyled textarea field

Additional details / screenshot

Versions

Plone 5.2.8 (5216)
CMF 2.5.4
Zope 4.8.1
Python 3.7.12 (default, Mar 14 2022, 07:11:45) [GCC 11.2.0]
PIL 6.2.2 (Pillow)
WSGI: On
Server: waitress 2.1.1
collective.easyform: 4.0.0

Screenshot