[A11y] Darken the GitHub star icon (#8288)

Darkens the orange GitHub star icon for 3:1 color contrast ratio.

Addresses #8286

Author: loic-sharma

src/Bootstrap/dist/css/bootstrap-theme.css

@@ -171,7 +171,8 @@
   .gh-star {
     font-size: 14px;
     line-height: 12px;
-    color: @brand-warning;
+    /* Use a slightly darker orange color to increase contrast for accessibility */
+    color: darken(@brand-warning, 4.5%);
   }
 
   .used-by {