Exclude phase banner from axe tests

Per UKGovernmentBEIS/regulated-professions-register@33be548
this fails axe tests because of the rule "All page content must be
contained by landmarks"

It's unclear how the rules that were violated were identified in that PR,
since it doesn't appear to add any logging of these. Here we've added
the logging, and when running the tests in the Cypress UI, we can see
that clicking on the error highlights the phase banner

Again according to that PR, the violation is due to the banner being
outside `<header>` and `<main>` elements. Apparently this is a [known
issue][1] with the component, but as the region rule is not a
requirement for WCAG, it should be okay to ignore for now

[1]: alphagov/govuk-frontend#1604

integration_tests/support/commands.ts

@@ -26,5 +26,5 @@ const logAccessibilityViolations = (violations: Result[]) => {
 Cypress.Commands.add('visitAndCheckAccessibility', (url: string) => {
   cy.visit(url)
   cy.injectAxe()
-  cy.checkA11y(undefined, undefined, logAccessibilityViolations)
+  cy.checkA11y({ exclude: [['.govuk-phase-banner']] }, undefined, logAccessibilityViolations)
 })