fix failing phpunit tests

tests/Unit/Helpers/DateDifferenceTest.php

@@ -32,13 +32,14 @@ class DateDifferenceTest extends TestCase
     /** @test */
     public function date_difference_returns_proper_months_and_days_format()
     {
-        // TODO: Need to fix, this should returns 1 months 9 days
-        $this->assertEquals('1 month 12 days', date_difference('2018-03-01', '2018-04-10', '%m month %d days'));
+        //according to https://www.datecalculator.org/date-difference-between-dates
+        $this->assertEquals('1 month 9 days', date_difference('2018-03-01', '2018-04-10', '%m month %d days'));
     }
 
     /** @test */
     public function date_difference_returns_proper_years_months_and_days_format()
     {
-        $this->assertEquals('1 year 1 month 12 days', date_difference('2017-03-01', '2018-04-10', '%y year %m month %d days'));
+        //according to https://www.datecalculator.org/date-difference-between-dates
+        $this->assertEquals('1 year 1 month 9 days', date_difference('2017-03-01', '2018-04-10', '%y year %m month %d days'));
     }
 }