Remove redundant role attributes from elements

[jon-kirwan]

What

Remove redundant role attributes from components.

Why

From GOV.UK Frontend:

We've made minor changes to the HTML of the page template, as well as the header, footer and pagination components.

You can update your HTML to remove the role attribute from some elements. These include the:

main role on the main element in the template
banner role on the header element in the Header component
contentinfo role on the footer element in the Footer component
navigation role on the nav element in the Pagination component

These roles were present to support legacy browsers, such as older versions of Internet Explorer. GOV.UK Frontend no longer supports these browsers, so you can now remove these roles.

This change was introduced in alphagov/govuk-frontend#4854.

See https://github.com/alphagov/govuk-frontend/releases/tag/v5.3.0