tests/test_nanshe/test_io/test_xjson.py: Fix tests for Python 3.
tests/test_nanshe/test_io/test_xjson.py: Fix tests for Python 3.

nanshe-org/nanshe,jakirkham/nanshe,DudLab/nanshe,nanshe-org/nanshe,jakirkham/nanshe,DudLab/nanshe