Fix: Update dependencies and resolve Sass deprecation warnings.

Updated jest to the latest version.
Addressed Sass deprecation warnings for color functions (red, green, blue) by migrating to color.channel().
Resolved data-uri deprecation by using url(data:...) format.

Note: Mixed-decls warnings persist but do not break current functionality; a more extensive refactor is needed for full resolution.

Author: milanowicz

CSSSassCollectionMixins.scss

@@ -150,12 +150,12 @@
 }
 
 @mixin BackgroundIcon ($filename, $filename-big: '', $width: auto, $height: auto) {
-  background-image: data-uri($filename);
+  background-image: url(data:image/png;base64,#{$filename});
   *background-image: url($filename);
   @include BackgroundSize($width $height);
 
   @media #{$high-dpi} {
-    background-image: data-uri($filename-big);
+    background-image: url(data:image/png;base64,#{$filename-big});
     *background-image: url($filename-big);
     @include BackgroundSize($width $height);
   }

test/_background.spec.scss

@@ -1,12 +1,13 @@
+@use 'sass:color';
 @use 'sass-tests' as *;
 
 @include true-describe('Background') {
   @include true-it('check BackgroundOpacity output') {
     @include true-assert {
       $Color: $background-color;
       $opacity: $opacity;
-      $RGBColor: rgb(red($Color), green($Color), blue($Color));
-      $RGBAColor: rgba(red($Color), green($Color), blue($Color), $opacity);
+      $RGBColor: rgb(color.channel($Color, 'red'), color.channel($Color, 'green'), color.channel($Color, 'blue'));
+      $RGBAColor: rgba(color.channel($Color, 'red'), color.channel($Color, 'green'), color.channel($Color, 'blue'), $opacity);
       @include true-output {
         @include BackgroundOpacity($Color, $opacity);
       }