Bump version of Python mentioned in docs

Author: adamtheturtle

docs/source/index.rst

@@ -8,7 +8,7 @@ Installation
 
    $ pip install vws-python
 
-This is tested on Python 3.8+.
+This is tested on Python 3.12+.
 Get in touch with ``adamdangoor@gmail.com`` if you would like to use this with another language.
 
 Usage