upgrade onnx.proto and protobuf (#446)

requirements.txt

-google/protobuf@v3.8.0 -DCMAKE_POSITION_INDEPENDENT_CODE=On -X subdir -Dprotobuf_BUILD_TESTS=Off
+google/protobuf@v3.11.0 -DCMAKE_POSITION_INDEPENDENT_CODE=On -X subdir -Dprotobuf_BUILD_TESTS=Off
 RadeonOpenCompute/rocm-cmake@b29ff83 --build
 ROCmSoftwarePlatform/rocBLAS@7197df74e5a1ba64ff967065872e5f86a3516637
 ROCmSoftwarePlatform/MIOpen@2.0.0

src/onnx/onnx.cpp

@@ -1897,6 +1897,8 @@ struct onnx_parser
         case onnx::AttributeProto::STRING:
         case onnx::AttributeProto::STRINGS:
         case onnx::AttributeProto::TENSORS:
+        case onnx::AttributeProto::SPARSE_TENSOR:
+        case onnx::AttributeProto::SPARSE_TENSORS:
         case onnx::AttributeProto::GRAPHS: return {};
         }
         MIGRAPHX_THROW("Invalid attribute type");