fix: [scss] Remove func to get color for print

The color for media print was moved into `themed()` mixin to prevent
repeating code. So there is no need for helper function `tp()` to get
theme color for media print.

Author: manid2

assets/styles/_main.scss

@@ -143,7 +143,10 @@ a {
       content: "(" attr(href) ")";
       text-decoration: underline;
       font-style: italic;
-      color: tp($text);
+
+      @include themed {
+        color: t($text);
+      }
     }
   }
 }

assets/styles/_themes.scss

@@ -115,7 +115,3 @@ $current-theme: null;
 @function t($key) {
   @return map-get($current-theme, $key);
 }
-
-@function tp($key) {
-  @return map-get(map-get($themes, "light"), "#{$key}");
-}