[Blog] New T-Shirt for 2025!

### Description
They had a t-shirt in 2025. We should document that.

### Details
- Is this related to Hacktoberfest?  Yep!
- Is it a new post, update, or correction? It's probably an update to the Hacktoberfest History post.  

### Additional Notes
![Image](https://github.com/user-attachments/assets/7e01f3b4-6fd0-4f44-abac-fdc591052703)