Fixed PyBind import

aidge_backend_cuda/__init__.py

-# Example 1: import .so generated by PyBind
-from aidge_backend_cuda.aidge_backend_cuda import *
-
-# Example 3: pure Python function equivalent to example 1 (example_func)
-from .example import *
+from aidge_backend_cuda.aidge_backend_cuda import * # import so generated by PyBind