Partial fix for issue eclipse/aidge/aidge_core#167

Partial fix for issue eclipse/aidge/aidge_core#167:

• Allow BatchNorm to handle any number of dimensions (in accordance with ONNX).

include/aidge/backend/cpu/operator/BatchNormImpl.hpp

@@ -29,7 +29,7 @@ using BatchNorm2D_Op = BatchNorm_Op<2>;
 using BatchNormImpl2D_cpu = OperatorImpl_cpu<BatchNorm_Op<2>,
     void(float,
         float,
-        const std::array<DimSize_t, 4> &,
+        const std::vector<DimSize_t> &,
         const void *,
         const void *,
         const void *,