Merge Sort in Python

[TishaJhabak1014]

Description

This issue will let me add a solution to important merge sort in Python.

[TishaJhabak1014]

@thesmartdeveloperr Issue created, Assign me this. You plz kindly add the hacktoberfest label now, and if the PR seems to be fine to you, do add the label hacktoberfest-accepted before merging as per the general way. Thank you.

[thesmartdeveloperr]

sure @TishaJhabak1014 go ahead. label will directly be added to the PR..