code_refactor: making is_number logic more readable

[waiz3ple]

Hi Jonschlinkert, I hope you're having a great day! I’ve updated the is_number logic to enhance its readability. While reviewing the code, I noticed that Number.isFinite was carefully used due to browser compatibility concerns at the time it was written. However, Number.isFinite now has significantly wider support and is more reliable compared to the older isFinite function, which is less precise. Let me know if there’s anything else you'd like me to address!