Validation CSS classes are not assigned to custom controls with Bootstrap 5.x

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Prerequisites

• I have searched for similar issues in both open and closed tickets and cannot find a duplicate.
• The issue still exists against the latest master branch of yii2-widget-activeform.
• This is not a usage question. I confirm having gone through and read the documentation for ActiveForm and ActiveField.
• This is not a general programming / coding question. (Those should be directed to the webtips Q & A forum).
• I have attempted to find the simplest possible steps to reproduce the issue.
• I have included a failing test as a pull request (Optional).

Steps to reproduce the issue

1. Go to https://demos.krajee.com/widget-details/active-field#custom-select
2. Do not select any option in the dropdowns.
3. Press Submit

Expected behavior and actual behavior

When I follow those steps, I see the validation message ("Weekdays cannot be blank") but the select element borders do not change colour are there is no background image. Element does not have is-invalid class.

I was expecting the select element borders to turn red and a background image appear to indicate error. The element should have is-invalid class.

Bootstrap 5 version for custom controls uses form-select for select and form-check-input for other custom controls. These are not used in activeform.js:

yii2-widget-activeform/src/assets/js/activeform.js

Line 159 in 697407c

var controls = ['.form-control', '.custom-control-input', '.custom-select', '.custom-range', '.custom-file-input'],

Environment

Browsers

• Google Chrome
• Mozilla Firefox
• Internet Explorer
• Safari

Operating System

• Windows
• Mac OS X
• Linux
• Mobile

Libraries

• jQuery version: 3.7.1
• yii2-widget-activeform version: v1.6.4

Isolating the problem

• This bug happens on the demos page
• The bug happens consistently across all tested browsers
• This bug happens when using yii2-widget-activeform without other plugins.