aria-expanded is not initialised

[flaviusdolca]

This issue refers to the rc-select component when using antd.

When the component is initialised, the aria-expanded attribute is not present. It will appear only after the first toggling of the select component. This will trigger the a11y scanner.

This issue can be fixed by changing the following line of code:

https://github.com/react-component/select/blob/master/src/Selector/Input.tsx#L94

to:
'aria-expanded': open || false,

#979