Improper use of aria-label in "System Powered By" block.

Problem/Motivation

The a11y tests in #3293469: Automated A11y tests in Nightwatch spotted the following problem

aXe rule: aria-allowed-attr - Elements must only use allowed ARIA attributes
	In element: .drupal-logo

Which I tracked down to core/themes/olivero/templates/block/block--system-powered-by-block.html.twig

<span class="drupal-logo" aria-label="{{ 'Drupal Logo'|t }}">
      {% include "@olivero/../images/drupal.svg" %}
    </span>

aria-label is used in a non-interactive span, but per MDN

Note: aria-label is intended for use on interactive elements, or elements made to be interactive via other ARIA declarations, when there is no appropriate text visible in the DOM that could be referenced as a label

That span is not interactive. The SVG itself should get the AT description. For reference, Deque has an article on this.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet