Add an extra line between the third-party heading and the FlatLaf link

Author: Synthird

README.md

@@ -5,6 +5,7 @@ Resize a GUI window by entering a number into textfields/textboxes.
 ![Textfield resizes window GUI](https://github.com/user-attachments/assets/e269345b-c4c7-4ddf-be35-eb20c0362c68)
 
 ## Third-party libraries used
+
 - [FlatLaf](https://www.formdev.com/flatlaf/) for the dark theme
 
 ## Download/Installation