test(alert): set aria label as a string

Author: brandyscarney

core/src/components/alert/test/a11y/index.html

@@ -87,7 +87,7 @@ <h1>Alert - A11y</h1>
             {
               text: 'Close',
               htmlAttributes: {
-                ariaLabel: 'close button',
+                'aria-label': 'close button',
                 'aria-labelledby': 'close-label',
               },
             },