Parsing error with special characters (æøåÆØÅ) in unquoted attribute value

[AudunWA]

Describe the bug
Special characters, in this case æ, ø, å, Æ, Ø or Å are not working correctly when parsing unquoted attributes.

To Reproduce
Steps to reproduce the behavior:
Run the reproduction script:

import { Window } from "happy-dom";
const window = new Window();
window.document.body.innerHTML = "<div id=æøåÆØÅ></div>";
const output = window.document.body.innerHTML;
// Expected output: <div id="æøåÆØÅ"></div>
// Actual output: <div id=""></div>
console.log(output);

Expected behavior
Expected output: <div id="æøåÆØÅ"></div>, as the input is valid HTML.

Device:

• happy-dom: 17.4.7
• Node.js: 22.15.1

Additional context
Probably related to #1237.