Switch from KaTeX to MathJax, ditching mmark

Signed-off-by: Abdulkadir Furkan Şanlı <abdulkadirfsanli@protonmail.com>

layouts/partials/extended_footer.html

@@ -3,7 +3,7 @@ To add an extended footer section, please create
 `layouts/partials/extended_footer.html` in your Hugo directory.
 -->
 
-<!-- KaTeX -->
+<!-- KaTeX
 <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/katex@0.11.1/dist/katex.min.css"
     integrity="sha384-zB1R0rpPzHqg7Kpt0Aljp8JPLqbXI3bhnPWROx27a9N0Ll6ZP/+DiW/UqRcLbRjq" crossorigin="anonymous">
 <script defer src="https://cdn.jsdelivr.net/npm/katex@0.11.1/dist/katex.min.js"
@@ -12,3 +12,15 @@ To add an extended footer section, please create
 <script defer src="https://cdn.jsdelivr.net/npm/katex@0.11.1/dist/contrib/auto-render.min.js"
     integrity="sha384-kWPLUVMOks5AQFrykwIup5lo0m3iMkkHrD0uJ4H5cjeGihAutqP0yW0J6dpFiVkI" crossorigin="anonymous"
     onload="renderMathInElement(document.body);"></script>
+-->
+
+<script>
+    MathJax = {
+        tex: {
+            inlineMath: [['$', '$'], ['\\(', '\\)']],
+            displayMath: [['$$', '$$'], ['\[', '\]']]
+        }
+    };
+</script>
+<script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js">
+</script>