[2.0.0-beta2] The regex for attribute props should allow the hyphen ("-") symbol

Problem/Motivation

I’m using Tailwind in my project, and as you know, most Tailwind classes contain hyphens ("-"). When I try to pass these classes through the attributes prop in a component element, the form validation rejects all the classes with hyphens. After investigating, I found that the regex used in the AttributesWidget::buildRegexPattern method doesn’t allow hyphens, it only permits words and spaces.

Additionally, for attribute names, why limit them to only alphabetic characters? Hyphens are commonly used in attribute names, especially for data attributes, such as data-slider="3"

Proposed resolution

Allow hyphens in both the regex for attribute names and attribute values

in AttributesWidget::buildRegexPattern method definition update the regex from:

    // Attribute names are a mix of ASCII lower and upper alphas.
    $attr_name = "[a-zA-Z]+";
    // Allow anything in attributes values, which are between double quotes.
    $double_quoted_value = '"[\s\w]*"';

to:

    // Attribute names are a mix of ASCII lower and upper alphas.
    $attr_name = "[a-zA-Z\-]+";
    // Allow anything in attributes values, which are between double quotes.
    $double_quoted_value = '"[\s\w\-]*"';