Added KNN regressor to models.py the advantage of this is it takes almost zero time to train because it only stores the data of the training part. and faster than all the models mentioned in the models.py file in training time as its zero in KNN regressor , it is also a non parametric models with only parameter that needs to be mentioned is the number of neighbours, adding to this as KNN doesn't undergo training we can add new data to it which doesn't affect the accuracy of the model. It is also very easy to implement and interpret as there is only one hyperparameter which is the number of neighbours, apart from this it's versatile and can be used as a regressor as well as classifier
PR fix for issue #6
Added KNN regressor to models.py the advantage of this is it takes almost zero time to train because it only stores the data of the training part. and faster than all the models mentioned in the models.py file in training time as its zero in KNN regressor , it is also a non parametric models with only parameter that needs to be mentioned is the number of neighbours, adding to this as KNN doesn't undergo training we can add new data to it which doesn't affect the accuracy of the model. It is also very easy to implement and interpret as there is only one hyperparameter which is the number of neighbours, apart from this it's versatile and can be used as a regressor as well as classifier