isWorktime reports true after close of work hours [bug]

[Tarang]

Say i had a calendar

package main

import (
	"fmt"
	"time"

	"github.com/rickar/cal/v2"
)

func main() {
	//Set work hours
	c := cal.NewBusinessCalendar()

    //Set hours as 10:00:00 am to 5:00:00 pm
	c.SetWorkHours(10*time.Hour+00*time.Minute, 5*time.Hour+0*time.Minute+00*time.Second)

	// Check if its work hours
	t := time.Date(0, 0, 0, 5, 0, 59, 0, time.UTC)
	isWorkHours := c.IsWorkTime(t) //Should return false

	fmt.Println(isWorkHours)
}

The output should be false as at 5:00:59 pm it is passed 5:00:00 pm by 59 seconds. The isWorkHours should take granularity down to seconds so that at 5:00:01 pm it is outside of work hours, vs 5:01:00 pm (a whole minute later).

Fixed in #109