Implemented eda_numeric_columns and added test cases

[rahulkuriyedath]

I have implemented explore_numeric_columns function and added tests for it in test_datascience_eda.py.

Few important notes:

• I added altair to the .toml file since i am using it. I updated poetry and hence the lock file has also been updated
• Regarding testing the plots, I spoke to Tiff yesterday and she said that - since its difficult to convert altair plots to png, it is okay if i just test for the labels and marks of the graph.

@charlessuresh , please review and let me know if something seems off