The version 1.3.0 has a bug with unicode charecters:
```
>>> from canonicaljson import encode_pretty_printed_json
>>> encode_pretty_printed_json({'a': 'à'})
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/erdnaxeli/.pyenv/versions/3.6.7/lib/python3.6/site-packages/canonicaljson.py", line 96, in encode_pretty_printed_json
return _pretty_encoder.encode(json_object).encode("ascii")
UnicodeEncodeError: 'ascii' codec can't encode character '\xe0' in position 12: ordinal not in range(128)
```
Signed-off-by: Alexandre Morignot <erdnaxeli@cervoi.se>
Co-authored-by: Alexandre Morignot <erdnaxeli@cervoi.se>
