Update form-field.pcss to make select chevron clickable

As a bug report from Jakub Dedek chevron inside select was not clickable (not opening select options), now it will be also clickable as rest of the select element.

source/css/atoms/form-field.pcss

@@ -73,6 +73,7 @@
     font-family: 'pirati-ui';
     /* chevron down */
     content: "\e925";
+    pointer-events: none;
   }
 }