Update src/canmatrix/cmjson.py
Update src/canmatrix/cmjson.py

Co-Authored-By: ebroecker <2f8b609dbeb7185fdfcf57d368d5b5c68333d7d2@gmail.com>
ebroecker/canmatrix,altendky/canmatrix,ebroecker/canmatrix,altendky/canmatrix