Allow each component to have its own colors and default to the global set

sass/form/select.sass

@@ -1,3 +1,5 @@
+$select-colors: $form-colors !default
+
 .select
   display: inline-block
   max-width: 100%
@@ -39,7 +41,7 @@
     &::after
       border-color: $input-hover-color
   // Colors
-  @each $name, $pair in $colors
+  @each $name, $pair in $select-colors
     $color: nth($pair, 1)
     &.is-#{$name}
       &:not(:hover)::after