Dev release for 0.6.3 (#1298)

This will be a small release that adds support for Keras 3 without
changing any dependencies yet.

Author: mattdangerw

keras_nlp/__init__.py

@@ -28,4 +28,4 @@
 from keras_nlp import utils
 
 # This is the global source of truth for the version number.
-__version__ = "0.6.2"
+__version__ = "0.6.3.dev0"