Remove unnecessary "type" attribute (#4956)

Author: davorg

_includes/head.html

@@ -9,7 +9,7 @@
 {%- comment %} https://docs.google.com/presentation/d/1rmxwWa9P6_xHqonmh5ONXRS-jPc5XKbnv99Rjkhe04s/present {% endcomment -%}
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 
-<script type="text/javascript">
+<script>
   document.documentElement.className = document.documentElement.className.replace(/\bno-js\b/g, '') + ' js ';
   {% if site.enable_copy_code_button -%}
     window.enable_copy_code_button = true;