Add the ability to hide the close button about pyqt-toast

[niklashenning]

Thanks for opening this issue!

This is actually something I wanted to add in the next release along with some other minor features. In the meantime, you can achieve this by setting the close button size to 0 like so: toast.setCloseButtonSize(QSize(0, 0))
This way, you don't have to add a transparent icon and the button won't still be clickable.

I'll implement this by adding an attribute like close_button_enabled and adjusting the __setup_ui method so the button will be hidden when it's set to False, which shouldn't take long.

Also thanks for submitting a pull request. I'll take a look at it (most likely over the weekend) and if everything looks good, I can release a new updated version with this feature and your fix in a couple of days

[fabiomanz]

Thank you very much for the fast reply and also the workaround.
Looking forward to the next release ;)