Add border to tag for customised colours

When a user customises their colours often the background is removed,
by adding a border we ensure that the tag component still keeps it's meaning.

src/components/tag/_tag.scss

@@ -4,10 +4,12 @@
 
 @include govuk-exports("govuk/component/tag") {
   .govuk-tag {
-    @include govuk-font($size: 16, $weight: bold, $line-height: 1.25);
+    @include govuk-font($size: 16, $weight: bold, $line-height: 1);
 
     display: inline-block;
-    padding: govuk-spacing(1) 8px 0;
+    padding: 4px 6px 1px;
+
+    border: 2px solid govuk-colour("blue");
 
     color: govuk-colour("white");
     background-color: govuk-colour("blue");
@@ -18,6 +20,7 @@
   }
 
   .govuk-tag--inactive {
+    border-color: govuk-colour("grey-1");
     background-color: govuk-colour("grey-1");
   }
 }