Bump version to 4.9.7

Update the __version__ string in src/__init__.py from 4.9.7b to 4.9.7, indicating a release from beta to stable.

Author: oop7

src/__init__.py

@@ -4,5 +4,5 @@
 A modern, user-friendly YouTube video downloader built with PySide6.
 """
 
-__version__ = "4.9.7b"
+__version__ = "4.9.7"
 __author__ = "oop7"