hot fix: True Range Feature

[martinb-ai]

Description

Fixes adding True Range command found when using SDK.

data= openbb.forecast.atr(dataset=data,close_column='Adj Close',high_column='High',low_column='Low')
print(data.head())

                 Open       High        Low      Close  Adj Close     Volume  \
date                                                                           
2019-12-12  66.945000  68.139999  66.830002  67.864998  66.485832  137310400   
2019-12-13  67.864998  68.824997  67.732498  68.787498  67.389549  133587600   
2019-12-16  69.250000  70.197502  69.245003  69.964996  68.543144  128186000   
2019-12-17  69.892502  70.442497  69.699997  70.102501  68.677849  114158400   
2019-12-18  69.949997  70.474998  69.779999  69.934998  68.513741  116028400   

            true_range  
date                    
2019-12-12    1.309998  
2019-12-13    1.092499  
2019-12-16    1.410004  
2019-12-17    0.742500  
2019-12-18    0.695000