This removes the empty C extension trick.

```
Traceback (most recent call last):

  File "<string>", line 7, in <module>

  File "<stdin>", line 2, in <module>

  File "d:\a\milksnake\milksnake\tests\res\nested\example\nested\__init__.py", line 1, in <module>

    from . import _native

  File "d:\a\milksnake\milksnake\tests\res\nested\example\nested\_native.py", line 7, in <module>

    lib = ffi.dlopen(os.path.join(os.path.dirname(__file__), '_native__libNone'), 0)

OSError: Cannot load library 'd:\\a\\milksnake\\milksnake\\tests\\res\\nested\\example\\nested\\_native__libNone': The specified module could not be found
```