`<Pds::TabNav>` causes accessibility violations when used as documented

[jgwhite]

Using <Pds::TabNav> as documented causes aXe violations.

For example, in the Waypoint codebase we use <Pds::TabNav> in the app.hbs template and we see the following violations from aXe (via ember-a11y-testing):

Promise rejected during "visiting builds page":

  The page should have no accessibility violations. Violations:

    [minor]: ARIA role should be appropriate for the element 
      Violated 1 time. Offending nodes are: 
        <nav class="pds-tabNav" role="tablist" data-test-tab-nav="">
      https://dequeuniversity.com/rules/axe/4.2/aria-allowed-role?application=axeAPI

    [critical]: Certain ARIA roles must contain particular children 
      Violated 1 time. Offending nodes are: 
        <nav class="pds-tabNav" role="tablist" data-test-tab-nav="">
      https://dequeuniversity.com/rules/axe/4.2/aria-required-children?application=axeAPI

[didoo]

Outdated. Closing now.