Feature: Change footer text color to match the default (#3969)

## Because
- The current text color of the footer is both inaccessible and also
just doesn't match the rest of TOP


## This PR
- Changes it to the default text colors


## Issue
Closes #3963 

## Pull Request Requirements
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- [x] I have thoroughly read and understand [The Odin Project
Contributing
Guide](https://github.com/TheOdinProject/theodinproject/blob/main/CONTRIBUTING.md)
- [x] 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
-   [x] The `Because` section summarizes the reason for this PR
- [x] The `This PR` section has a bullet point list describing the
changes in this PR
- [x] I have verified all tests and linters pass after making these
changes.
- [x] If this PR addresses an open issue, it is linked in the `Issue`
section

app/views/shared/_footer.html.erb

@@ -74,7 +74,7 @@
       </div>
     </div>
     <div class="mt-16 border-t border-gray-900/10 dark:border-white/10 pt-8 sm:mt-20 lg:mt-24">
-      <p class="text-xs leading-5 text-gray-400">&copy; <%= Time.current.year %> The Odin Project. All rights reserved.</p>
+      <p class="text-xs leading-5 text-gray-600 dark:text-gray-300">&copy; <%= Time.current.year %> The Odin Project. All rights reserved.</p>
     </div>
   </div>
 </footer>