feat: Update mermaid version to same as GitHub (#58)

# Mermaid version

- old 10.9.1
- new 11.3.0

# How to check

```markdown
  ```mermaid
  info
  ```
```

cmd/template.html

@@ -189,7 +189,7 @@
         loadmd();
       })()
     </script>
-    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/mermaid/10.9.1/mermaid.min.js"></script>
+    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/mermaid/11.3.0/mermaid.min.js"></script>
     <article id="markdown-body" class="markdown-body"></article>
   </body>
 </html>