message: Use explicit opset of Unsqueeze from nGraph
  The change is needed due to removing default opset namespace for Unsqueeze
  in the scope of this refactoring activity:
diff: @@ -607,7 +607,7 @@ public:
  auto priorBox = std::make_shared<ngraph::op::PriorBoxClustered>(slice_layer, slice_image, attrs);
  auto axis = std::make_shared<ngraph::op::Constant>(ngraph::element::i64, ngraph::Shape{1}, std::vector<int64_t>{0});
  - auto unsqueeze = std::make_shared<ngraph::op::Unsqueeze>(priorBox, axis);
  + auto unsqueeze = std::make_shared<ngraph::op::v0::Unsqueeze>(priorBox, axis);
  return Ptr<BackendNode>(new InfEngineNgraphNode(unsqueeze));
  }
  else
  @@ -628,7 +628,7 @@ public:
  auto priorBox = std::make_shared<ngraph::op::PriorBox>(slice_layer, slice_image, attrs);
  auto axis = std::make_shared<ngraph::op::Constant>(ngraph::element::i64, ngraph::Shape{1}, std::vector<int64_t>{0});
  - auto unsqueeze = std::make_shared<ngraph::op::Unsqueeze>(priorBox, axis);
  + auto unsqueeze = std::make_shared<ngraph::op::v0::Unsqueeze>(priorBox, axis);
  return Ptr<BackendNode>(new InfEngineNgraphNode(unsqueeze));
  }
  }
  