rknn2.1.0导出模型失败，example都用不了

都是在最后导出模型的时候导出不了

E build: Catch exception when building RKNN model!
E build: Traceback (most recent call last):
E build:   File "rknn/api/rknn_base.py", line 2149, in rknn.api.rknn_base.RKNNBase.build
E build:   File "rknn/api/rknn_base.py", line 1062, in rknn.api.rknn_base.RKNNBase._generate_rknn
E build: ImportError: libprotobuf.so.10: cannot open shared object file: No such file or directory
Build model failed!