update dev version to 0.3.1.dev0 (#153)

Author: sachinprasadhs

keras_rs/src/version.py

@@ -1,7 +1,7 @@
 from keras_rs.src.api_export import keras_rs_export
 
 # Unique source of truth for the version number.
-__version__ = "0.2.2.dev0"
+__version__ = "0.3.1.dev0"
 
 
 @keras_rs_export("keras_rs.version")