Update FactorialOfANumber.py

[itsjatin135s]

Description

I had modified the code so now it will only work for positive no. only

Issue No.- #323

Type issue number after hash(#)

Checklist

• [x] Yes, this task assigned to me.
• [x] My code follows the style guidelines(Clean Code) of this project
• [x] I have performed a self-review of my own code
• [x] My Filename is in camelCase format
• [x] I have added Problem statement, Problem link in file.

[aayushi-droid]

Please mention the correct issue number.

[itsjatin135s]

Hey sorry for the mistake I had corrected it please review. its issue #323 Thank You