canonicalUrl post metadata doesn't actually update the canonical url rendered on the page

**Describe the bug**
When you add the `canonicalUrl` field to the top of a post, i.e.:

```
---
title: My Blog Post
date: '2025-10-22'
tags: ['someTag']
draft: false
summary: A blogpost demonstrating the bug
canonicalUrl: https://www.someWebsite.com/some/path
---
```

The `<link rel="canonical">` tag doesn't actually get updated with the canonical url