Ensure dropdown toggles show with border in high contrast mode

Update _dropdown.scss (#12365)

CHANGELOG.txt

@@ -31,6 +31,7 @@ Changelog
  * Fix: Prevent popular tags filter from generating overly complex queries when not filtering (Matt Westcott)
  * Fix: Fix content path links in usage view to scroll to the correct element (Sage Abdullah)
  * Fix: Always show the minimap toggle button (Albina Starykova)
+ * Fix: Ensure that dropdown button toggles show with a border in high contrast mode (Ishwari8104, LB (Ben) Johnston)
  * Docs: Upgrade Sphinx to 7.3 (Matt Westcott)
  * Docs: Document how to customize date/time format settings (Vince Salvino)
  * Docs: Create a new documentation section for deployment and move fly.io deployment from the tutorial to this section (Vince Salvino)

CONTRIBUTORS.md

@@ -835,6 +835,7 @@
 * Sanjeev Holla S
 * Shubham Mukati
 * Matthew Scouten
+* Ishwari8104
 
 ## Translators
 

client/scss/components/_dropdown.scss

@@ -1,5 +1,5 @@
 .w-dropdown__toggle {
-  @apply w-px-2 w-text-text-label w-bg-transparent;
+  @apply w-px-2 w-text-text-label w-bg-transparent w-border-2 w-border-transparent;
 }
 
 .w-dropdown__toggle--icon {

docs/releases/6.3.md

@@ -49,6 +49,7 @@ This release adds formal support for Django 5.1.
  * Ensure invalid submissions are marked as dirty edits on load to trigger UI and browser warnings for unsaved changes, restoring previous behavior from Wagtail 5.2 (Sage Abdullah)
  * Update polldaddy oEmbed provider to use the crowdsignal URL (Matthew Scouten)
  * Remove polleverywhere oEmbed provider as it this application longer supports oEmbed (Matthew Scouten)
+ * Ensure that dropdown button toggles show with a border in high contrast mode (Ishwari8104, LB (Ben) Johnston)
 
 ### Documentation