No event received for humb buttons on windows

Using this script I can only receive events for mouse buttons 1, 2 and 3. Nothing shown when pressing thumb buttons on Windows 10.

```python
from pymouse import PyMouseEvent

class Mouse(PyMouseEvent):
    def click(self, x, y, button, press):
        print(button)

C = Mouse()
C.run()

```
The same script works well under linux and prints 8, 9 for thumb buttons.