Update MathJax CDN

scipost/templates/scipost/base.html

@@ -55,7 +55,7 @@
       processEscapes: true
       }});
     </script>
-    <script type="text/javascript" async src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-MML-AM_CHTML"></script>
+    <script type="text/javascript" async src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-MML-AM_CHTML"></script>
 
     {% render_bundle 'main' 'js' %}
     {% render_bundle 'bootstrap' 'js' %}