fix(curriculum): allow optional final css semi-colon (#43545)

* fix for issue: #43536, final css property optional semi-colon

* accidentally left a "y" at the end of the sentence

* replaced regex with CSSHelp

* removed trailing white-space

curriculum/challenges/english/01-responsive-web-design/applied-visual-design/center-an-element-horizontally-using-the-margin-property.md

@@ -22,7 +22,7 @@ Center the `div` on the page by adding a `margin` property with a value of `auto
 The `div` should have a `margin` set to `auto`.
 
 ```js
-assert(code.match(/margin:\s*?auto;/g));
+assert(new __helpers.CSSHelp(document).getStyle('div')?.margin === 'auto');
 ```
 
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