[fix] ci: disable run of mdbook deploy on forks

[alexandrebrg]

Closes #

📑 Description

It disables deploy job of mdbook CI when running on forks

✅ Checks

• [ ] My pull request adheres to the code style of this project
• [ ] My code is documented
• [ ] I provided unitary tests or procedure to test my code
• [ ] My PR have a clear description of what my code is supposed to do

ℹ Additional Information