Upgrade font awesome to 6.2.1

style/fa/_list.scss

@@ -1,18 +1,18 @@
-// List Icons
+// icons in a list
 // -------------------------
 
 .#{$fa-css-prefix}-ul {
   list-style-type: none;
-  margin-left: $fa-li-width * 5/4;
+  margin-left: var(--#{$fa-css-prefix}-li-margin, #{$fa-li-margin});
   padding-left: 0;
 
   > li { position: relative; }
 }
 
 .#{$fa-css-prefix}-li {
-  left: -$fa-li-width;
+  left: calc(var(--#{$fa-css-prefix}-li-width, #{$fa-li-width}) * -1);
   position: absolute;
   text-align: center;
-  width: $fa-li-width;
+  width: var(--#{$fa-css-prefix}-li-width, #{$fa-li-width});
   line-height: inherit;
 }