fix: add test to ensure the innerText of labels doesn't change (#43803)

For the check-radio-buttons-and-checkboxes-by-default exercise,
campers are able to pass the exercise if the checked attribute is
written in an incorrect syntax. This PR checks the innerText of the
elements which are being added the 'checked' attribute and ensures that
their value doesn't change.
Fixes #43750

curriculum/challenges/english/01-responsive-web-design/basic-html-and-html5/check-radio-buttons-and-checkboxes-by-default.md

@@ -35,6 +35,18 @@ Your first checkbox on your form should be checked by default.
 assert($('input[type="checkbox"]').prop('checked'));
 ```
 
+You should not change the inner text of the `Indoor` label.
+
+```js
+assert.equal(document.querySelector('label[for="indoor"]')?.innerText?.trim(), 'Indoor');
+```
+
+You should not change the inner text of the `Loving` label.
+
+```js
+assert.equal(document.querySelector('label[for="loving"]')?.innerText?.trim(), 'Loving');
+```
+
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