Infra: Add site analytics via Plausible (python#4398)

Author: AA-Turner

pep_sphinx_extensions/pep_theme/templates/page.html

@@ -63,5 +63,7 @@ <h2>Contents</h2>
     <script src="{{ pathto('_static/colour_scheme.js', resource=True) }}"></script>
     <script src="{{ pathto('_static/wrap_tables.js', resource=True) }}"></script>
     <script src="{{ pathto('_static/sticky_banner.js', resource=True) }}"></script>
+    <script src="https://analytics.python.org/js/script.outbound-links.js"
+            data-domain="peps.python.org" defer></script>
 </body>
 </html>