change Slice attr to int64

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

@@ -33,9 +33,9 @@ void SliceImpl_cpu_forward_kernel(const typename Slice_Op::Attrs& attrs,
     for(std::size_t i=0; i<nbAxes;++i)
     {
         // For each slice operation get the params and cast them to size_t
-        int axis_ = std::get<2>(attrs)[i];
-        int start_ = std::get<0>(attrs)[i];
-        int end_ = std::get<1>(attrs)[i];
+        std::int32_t axis_ = std::get<2>(attrs)[i];
+        std::int32_t start_ = std::get<0>(attrs)[i];
+        std::int32_t end_ = std::get<1>(attrs)[i];
         std::size_t axis = axis_>=0?axis_:axis_+inputDims.size();
         std::size_t start = start_>=0?start_:start_+inputDims[axis];
         std::size_t end = end_>=0?end_:end_+inputDims[axis];