added XGBRegressor in machine learning

[aishwarya24bhagwat]

Here is my contribution XGBRegressor

[gitpod-io[bot]]

[hritik5102]

@aishwarya24bhagwat LGTM, Please change the path of the file, It is in the root directory instead add inside Machine_learning and could you please add the documentation in the script or create README.md file.

Thank you :)