Fix: Add ejs to Prism language configuration

[JoshDevHub]

Because

Code examples using ejs weren't being given proper syntax highlighting.

This PR

• adds "ejs" to the languages array in the configuration for Prism (the library used to provide syntax highlighting).

Issue

Closes #4497

Additional Information

Pull Request Requirements

• I have thoroughly read and understand The Odin Project Contributing Guide
• The title of this PR follows the keyword: brief description of change format, using one of the following keywords:
  • Feature - adds new or amends existing user-facing behavior
  • Chore - changes that have no user-facing value, refactors, dependency bumps, etc
  • Fix - bug fixes
• The Because section summarizes the reason for this PR
• The This PR section has a bullet point list describing the changes in this PR
• I have verified all tests and linters pass after making these changes.
• If this PR addresses an open issue, it is linked in the Issue section
• If applicable, this PR includes new or updated automated tests

[JoshDevHub]

To QA:

1. Visit the preview tool in the review app (the path is /lessons/preview)
2. Paste this code in. Fence it with triple backticks and add the language ejs after the opening set of backticks:

<nav>
   <ul>
     <% for (let i = 0; i < links.length; i++) { %>
       <li>
         <a href="<%= links[i].href %>">
           <span> <%= links[i].text %> </span>
         </a>
       </li>
     <% } %>
   </ul>
 </nav>

3. Preview the markup and confirm that there's highlighting.

Here's what it currently looks like on main for comparison:

[MaoShizhong]

Nice and simple, thanks @JoshDevHub.
Had thought it just needed this, but didn't see html and wasn't sure if there were other things as well. But then I realised that markup contains html so has that covered there 😅

Test deployment's working well!