Add missing aria-label to upgrade banner dismiss button

wagtail/admin/templates/wagtailadmin/home/upgrade_notification.html

@@ -25,6 +25,7 @@
         data-action="w-dismissible#toggle"
         {% if dismissible_value %}data-w-dismissible-value-param="{{ dismissible_value }}"{% endif %}
         data-w-upgrade-target="dismiss"
+        aria-label="{% trans 'Close' %}"
         class="w-ml-auto w-flex w-items-center w-justify-center w-bg-transparent w-rounded-full w-p-0 w-w-8 w-h-8
                w-text-current
                w-border

wagtail/admin/tests/test_upgrade_notification.py

@@ -78,6 +78,7 @@ class TestUpgradeNotificationPanel(WagtailTestUtils, TestCase):
         )
         toggle = soup.select_one("[data-action='w-dismissible#toggle']")
         self.assertIsNotNone(toggle)
+        self.assertEqual(toggle.get("aria-label"), "Close")
         self.assertIsNone(toggle.get(self.ATTR_LAST_DISMISSED_VALUE))
 
     @override_settings(WAGTAIL_ENABLE_UPDATE_CHECK=False)
@@ -115,6 +116,7 @@ class TestUpgradeNotificationPanel(WagtailTestUtils, TestCase):
                 )
                 toggle = soup.select_one("[data-action='w-dismissible#toggle']")
                 self.assertIsNotNone(toggle)
+                self.assertEqual(toggle.get("aria-label"), "Close")
                 self.assertIsNone(toggle.get(self.ATTR_LAST_DISMISSED_VALUE))
 
     def test_render_html_dismissed_version(self):
@@ -140,6 +142,7 @@ class TestUpgradeNotificationPanel(WagtailTestUtils, TestCase):
         )
         toggle = soup.select_one("[data-action='w-dismissible#toggle']")
         self.assertIsNotNone(toggle)
+        self.assertEqual(toggle.get("aria-label"), "Close")
         self.assertEqual(
             toggle.get(self.ATTR_LAST_DISMISSED_VALUE),
             "6.2.2",