fix: update sidebar breakpoint to match breakpoints used in other components

Author: sghoweri

packages/uikit-workshop/src/sass/scss/05-themes/_sidebar-theme.scss

@@ -4,7 +4,7 @@
 
 $pl-sidebar-width: 14rem; //Define sidebar width for calculating dimensions
 
-@media all and (min-width: 48em) {
+@media all and (min-width: $pl-bp-med) {
   /**
     * A theme that places displays the header as a sidebar
     */