fix(curriculum): replace head content regex (freeCodeCamp#55924)

Author: lasjorg

curriculum/challenges/english/14-responsive-web-design-22/learn-responsive-web-design-by-building-a-piano/612e83ec2eca1e370f830511.md

@@ -33,7 +33,7 @@ assert.strictEqual(document.querySelectorAll('link')?.length, 1);
 Your `link` element should be inside your `head` element.
 
 ```js
-const headContentRegex = /(?<=<head\s*>)(?:.|\s*)*?(?=<\/head\s*>)/;
+const headContentRegex = /(?<=<head\s*>)[\S|\s]*(?=<\/head\s*>)/;
 const headElementContent = code.match(headContentRegex);
 
 const headElement = document.createElement("head");