Fix conditional rendering of tag and category section (alshedivat#2678)

### Overview
This PR fixes an issue where unnecessary horizontal lines were displayed
when there were no tags or categories present. The tag and category
container is now conditionally rendered, ensuring it only appears when
there are tags or categories to display.

no tags meaning, in _config.yml
```
display_tags: []
display_categories: []
```

### Before and After
The difference is illustrated in the images below:
- **First Image (Fixed)**: Shows the correct behavior with no extra
lines when tags or categories are absent.
- **Second Image (Current)**: Demonstrates the issue with unwanted
horizontal lines appearing when no tags or categories are present.


![image](https://github.com/user-attachments/assets/08becad5-9a34-4b6c-8a69-25206d9097da)

![image](https://github.com/user-attachments/assets/e36390cc-3104-4aa2-a047-a7fa8289e664)

### Impact
This change improves the visual consistency and cleanliness of the theme
by preventing unnecessary elements from being rendered, particularly in
cases where there are no tags or categories defined.

_pages/blog.md

@@ -29,7 +29,7 @@ pagination:
   </div>
   {% endif %}
 
-{% if site.display_tags or site.display_categories %}
+{% if site.display_tags and site.display_tags.size > 0 or site.display_categories and site.display_categories.size > 0 %}
 
   <div class="tag-category-list">
     <ul class="p-0 m-0">