Issue on the button view constructor

[defender4git]

Hi,
Nice job done on this package. 2.0.0

I found a bug in the package, button view dart file.
in line 36 / 37 where we have the constructor.
"{" placed on line 37 instead of line 36.

impact:
Does not allow the Buttons. resolves

correction:

Edited the button_view.dart file on the lines mentioned above.

thank you