[upd] bracket delimiter for Tensor representation

Context

'{' bracket delimiter was used because of Tensor generation during export as it created valid C++ style arrays. Now that Tensors are converted to arrays and then lists to generate export Tensors, the string representatin of Tensor is not used for this functionality anymore and can be made compatible with NumPy representation.

Detailed major modifications

• upd: Tensor representation went from "{1, 2, 3}" to "[1, 2, 3]"
• upd: aidge_export_aidge PyBind version and 'main.cpp' files