Use modern GA loading code

docs/_templates/layout.html

@@ -0,0 +1,13 @@
+{% extends "!layout.html" %}
+
+{%- block extrahead %}
+<!-- Google Analytics -->
+<script>
+window.ga=window.ga||function(){(ga.q=ga.q||[]).push(arguments)};ga.l=+new Date;
+ga('create', 'UA-20736318-2', 'auto');
+ga('send', 'pageview');
+</script>
+<script async="async" src='https://www.google-analytics.com/analytics.js'></script>
+<!-- End Google Analytics -->
+  {{ super() }}
+{% endblock %}

docs/conf.py

@@ -114,7 +114,6 @@ html_theme_options = {
     'show_powered_by': False,
     'fixed_sidebar': True,
     'sidebar_collapse': True,
-    'analytics_id': 'UA-20736318-2',
     'github_button': False,
     'github_banner': True,
     'github_user': 'kovidgoyal',