fix(checkbox-toggle): update disabled toggle circle to neutral-90 (#5224)

* fix(checkbox-toggle): update disabled toggle circle to neutral-90

* docs(RELEASENOTES): update README notes

Author: Amarnath510

RELEASENOTES.general.md

@@ -1,6 +1,11 @@
 <!-- Release notes authoring guidelines: http://keepachangelog.com/ -->
 <!-- On release, add general notes here. In time the legacy release notes will be add to this -->
 
+## 2.21.4 - Upcoming
+
+## Fixed
+- Updated disabled checkbox-toggle color.
+
 ## 2.21.3 - June 29, 2023
 
 ## Fixed

ui/components/checkbox-toggle/base/_index.scss

@@ -229,7 +229,7 @@
 
         &:after {
           // @todo consider shared hooks for inputs
-          background-color: var(--slds-g-color-neutral-base-80, #{$color-background-input-checkbox-disabled});
+          background-color: var(--slds-g-color-neutral-base-90, #{$color-background-input-checkbox-disabled});
         }
 
         &:hover,