Correction of bug when number of nano seconds equals a full day

Author: r3mv

fastexcel-reader/src/main/java/org/dhatim/fastexcel/reader/Cell.java

@@ -99,6 +99,11 @@ public LocalDateTime asDate() {
     private LocalDateTime convertToDate(double value) {
         int wholeDays = (int) Math.floor(value);
         long millisecondsInDay = (long) (((value - wholeDays) * DAY_MILLISECONDS) + 0.5D);
+        // sometimes the rounding for .9999999 returns the whole number of ms a day
+        if(millisecondsInDay == DAY_MILLISECONDS) {
+            wholeDays +=1;
+            millisecondsInDay= 0;
+        }
 
         int startYear = 1900;
         int dayAdjust = -1; // Excel thinks 2/29/1900 is a valid date, which it isn't