v0.8.7

• New widget : slimSelectInput(), an alternative select menu.
• Updated virtual-select to 1.0.45, see https://github.com/sa-si-dev/virtual-select/releases.
• airDatepickerInput() & updateAirDateInput(): added a tz argument to specify timezone.
• checkboxGroupButtons() & radioGroupButtons(): fixed justified layout when using individual buttons.