Fix duplicate class attribute in image chooser (#12245)

CHANGELOG.txt

@@ -11,6 +11,7 @@ Changelog
  * Fix: Prevent page type business rules from blocking reordering of pages (Andy Babic, Sage Abdullah)
  * Fix: Improve layout of object permissions table (Sage Abdullah)
  * Fix: Fix typo in aria-label attribute of page explorer navigation link (Sébastien Corbin)
+ * Fix: Reinstate transparency indicator on image chooser widgets (Sébastien Corbin)
  * Docs: Upgrade Sphinx to 7.3 (Matt Westcott)
  * Docs: Document how to customise date/time format settings (Vince Salvino)
  * Maintenance: Removed support for Python 3.8 (Matt Westcott)

docs/releases/6.3.md

@@ -26,6 +26,7 @@ This release adds formal support for Django 5.1.
  * Prevent page type business rules from blocking reordering of pages (Andy Babic, Sage Abdullah)
  * Improve layout of object permissions table (Sage Abdullah)
  * Fix typo in aria-label attribute of page explorer navigation link (Sébastien Corbin)
+ * Reinstate transparency indicator on image chooser widgets (Sébastien Corbin)
 
 ### Documentation
 

wagtail/images/templates/wagtailimages/widgets/image_chooser.html

@@ -2,5 +2,5 @@
 
 {% block chosen_icon %}
     {# Empty alt because the chosen item’s title is already displayed next to the image. #}
-    <img class="chooser__image" data-chooser-image alt="" class="show-transparency" decoding="async" height="{{ preview.height }}" src="{{ preview.url }}" width="{{ preview.width }}">
+    <img class="chooser__image show-transparency" data-chooser-image alt="" decoding="async" height="{{ preview.height }}" src="{{ preview.url }}" width="{{ preview.width }}">
 {% endblock chosen_icon %}