Rolls back to the new version of Matjax

docs/_includes/head_custom.html

@@ -4,17 +4,22 @@
 {% elsif site.latex == "mathjax" %}
 
 <!-- Use MathJax to Render LaTeX in MarkDown -->
-<script type="text/x-mathjax-config">
-  MathJax.Hub.Config({
-    tex2jax: {inlineMath: [['$','$']]},
-    "HTML-CSS": { linebreaks: { automatic: true } },
-    CommonHTML: { linebreaks: { automatic: true } },
-    SVG: { linebreaks: { automatic: true } }
-  });
+<script>
+  MathJax = {
+    tex: {
+      inlineMath: [
+        ["$", "$"],
+        ["\\(", "\\)"],
+      ],
+      processEscapes: true,
+    },
+  };
 </script>
 <script
   type="text/javascript"
-  src="https://cdn.jsdelivr.net/npm/mathjax@2/MathJax.js?config=TeX-AMS_HTML"
+  id="MathJax-script"
+  async
+  src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"
 ></script>
 
 {% elsif site.latex == "katex" %}