Remove unnecessary `dl` element from "Date modified" text

Patch will current state of merge request.

Hmmm interesting, Canada.ca is still using a description list for this block. What accessibility issue is being flagged? I think a description list is semantically correct here. The connection between the "Date Modified" label and the actual date is explicitly declared, aiding screen readers in understanding the relationship. I tend to lean towards what Canada.ca has implemented especially for common elements such as this.

The current state matches upstream:

https://wet-boew.github.io/GCWeb/sites/date-modified/date-modified-en.html