fix: add/subtract business days infinite loop

[lucianm05]

No description provided.

[lucianm05]

related to this issue: #6

the current implementation enters an infinite loop if the provided number is negative

[antonio-pbilby]

Isn't it possible to just use the absolute value (Math.abs()) of the given number instead of declaring different methods depending on the sign of the number?

[lucianm05]

it is possible, but for my use case I would have preferred if the days had been reduced, not to check if the value I'm passing to the function is negative and calling the subtractBusinessDays function instead

at least that's the behavior I was expecting from the addBusinessDays with a negative value