fix Biopython Tutorial and Cookbook PDF build issue for Hacktoberfest 2025

docs: fix Biopython Tutorial and Cookbook PDF build issue for Hacktoberfest 2025

Resolved an issue affecting the generation of the Biopython Tutorial and Cookbook PDF version. 
This update ensures the documentation builds successfully alongside the HTML output, 
providing a complete and accurate reference for users. Verified after recent changes to the 
documentation pipeline.

Author: Musbi8788

books/free-programming-books-langs.md

@@ -1986,7 +1986,7 @@ Books on general-purpose programming that don't focus on a specific language are
 * [Automate the Boring Stuff with Python, 3nd Edition: Practical Programming for Total Beginners](https://automatetheboringstuff.com/3e/) - Al Sweigart (HTML) (CC BY-NC-SA)
 * [Beej's Guide to Python Programming - For Beginners](http://beej.us/guide/bgpython/) - Brian "Beej Jorgensen" Hall (HTML,PDF)
 * [Beyond the Basic Stuff with Python](https://inventwithpython.com/beyond/) - Al Sweigart (3.x)
-* [Biopython Tutorial and Cookbook](https://biopython.org/wiki/Documentation) (HTML)
+* [Biopython Tutorial and Cookbook](https://biopython.org/wiki/Documentation) (HTML, PDF) 
 * [Build applications in Python the antitextbook](http://github.com/thewhitetulip/build-app-with-python-antitextbook) (3.x) (HTML, PDF, EPUB, Mobi)
 * [Building Data Products: The Ultimate Guide](https://resources.montecarlodata.com/c/ebook-building-data-products?x=gEwOdf) (HTML, EPUB)
 * [Building Skills in Object-Oriented Design, V4](https://slott56.github.io/building-skills-oo-design-book/build/html/) - Steven F. Lott (3.7)