fix billable calculation on timesheet restart (#3225)

src/Validator/Constraints/TimesheetLongRunningValidator.php

@@ -61,7 +61,8 @@ final class TimesheetLongRunningValidator extends ConstraintValidator
         }
 
         $duration = $timesheet->getEnd()->getTimestamp() - $timesheet->getBegin()->getTimestamp();
-        $minutes = (int) $duration / 60;
+        // float on purpose, because one second more than the configured minutes is already too long
+        $minutes = $duration / 60;
 
         if ($minutes < $maxMinutes) {
             return;