Read "maxlength" attribute instead of "maxLength" in "-guard-for-maxlength.ts"

[shubham88fru]

I had opened this a while back but didn't end up creating a PR.

background: The following piece of code in "-guard-for-maxlength.ts" reads "maxLength" (camelcase") attribute instead of "maxlength" (lowercase)

ember-test-helpers/addon/addon-test-support/@ember/test-helpers/dom/-guard-for-maxlength.ts

Line 22 in 3b83f12

!!Number(element.getAttribute('maxLength')) &&

As per this MDN document, the actual attribute is "maxlength" (lowercase) and NOT "maxLength" (camel case).

In fact, in the same file, few lines below, the following line of code does this correctly.

ember-test-helpers/addon/addon-test-support/@ember/test-helpers/dom/-guard-for-maxlength.ts

Line 41 in 3b83f12

const maxlength = element.getAttribute('maxlength');

I think, this should be fixed for consistency and correctness.
Please let me know if I can work on this and can create a PR.

Thanks.

[shubham88fru]

@rwjblue @kategengler - I'd be happy to do this change as my first contribution to open source. Please have a look.

[shubham88fru]

@NullVoxPopuli - created PR for this change.