Gradient Boosting Regressor (#2298)

* Stock market prediction using greadient boosting

* To reverse a string using stack

* To reverse string using stack

* Predict Stock Prices Python & Machine Learning

* Gradient boosting regressor on boston dataset

* Gradient boosting regressor implementation

* Gradient boosting regressor

* Gradient boosting regressor

* Gradient boosting regressor

* Removing files

* GradientBoostingRegressor example

* Demo Gradient Boosting

* Demo Gradient boosting

* demo of gradient boosting

* gradient boosting demo

* Fix spelling mistake

* Fix formatting

Co-authored-by: John Law <johnlaw.po@gmail.com>