update example code for libtorch 1.2 API

Author: deepali-c

advanced_source/torch_script_custom_ops.rst

@@ -634,13 +634,13 @@ custom operator, that loads and executes a serialized TorchScript model:
     }
 
     // Deserialize the ScriptModule from a file using torch::jit::load().
-    std::shared_ptr<torch::jit::script::Module> module = torch::jit::load(argv[1]);
+    torch::jit::script::Module module = torch::jit::load(argv[1]);
 
     std::vector<torch::jit::IValue> inputs;
     inputs.push_back(torch::randn({4, 8}));
     inputs.push_back(torch::randn({8, 5}));
 
-    torch::Tensor output = module->forward(std::move(inputs)).toTensor();
+    torch::Tensor output = module.forward(std::move(inputs)).toTensor();
 
     std::cout << output << std::endl;
   }