New python-msgpack version brokes connector

[RepentantGopher]

New version of python-msgpack library was released which enforce only string keys in map by default.
This change brokes whole connector because version of python msgpack library is not enforced in requirements.

Commit msgpack/msgpack-python@d8e3cf0

Error on connection to tarantool:

test_tags.py:6: in <module>
    from .common import (
common.py:22: in <module>
    operational_storage = tarantool.connect("localhost", 3303, "tarantool", "tarantool")
venv/lib/python3.7/site-packages/tarantool/__init__.py:51: in connect
    encoding=encoding)
venv/lib/python3.7/site-packages/tarantool/connection.py:130: in init
    self.connect()
venv/lib/python3.7/site-packages/tarantool/connection.py:208: in connect
    raise NetworkError(e)
E   tarantool.error.NetworkError: int is not allowed for map key

[pcdinh]

I got the same issue in Ubuntu 18.04, Python 3.8.2, Tarantool 0.6.6

[Totktonada]

Should be fixed with PR #156.

[artembo]

In the new release of msgpack also encoding parameter was removed.

Remove encoding option from the Packer and Unpacker.

@Totktonada suggested

If the encoding option is given to the connector, then you can programmatically go through recursively and do .decode (encoding = 'utf-8') for all bytes (Python 3) or str (Python 2) values. It seems like this should work, and fully transparently support everything that was previously supported:

Python 2:

>>> import msgpack
>>> msgpack.unpackb(b'\xd9\x08\xd0\xb0\xd0\xb1\xd0\xb2\xd0\xb3', raw=True).decode(encoding='utf-8')
u'\u0430\u0431\u0432\u0433'
>>> msgpack.unpackb(b'\xd9\x08\xd0\xb0\xd0\xb1\xd0\xb2\xd0\xb3', encoding='utf-8')
u'\u0430\u0431\u0432\u0433'

Python 3:

>>> import msgpack
>>> msgpack.unpackb(b'\xd9\x08\xd0\xb0\xd0\xb1\xd0\xb2\xd0\xb3', raw=True).decode(encoding='utf-8')
'абвг'
>>> msgpack.unpackb(b'\xd9\x08\xd0\xb0\xd0\xb1\xd0\xb2\xd0\xb3', encoding='utf-8')
__main__:1: DeprecationWarning: encoding is deprecated, Use raw=False instead.
'абвг'

[Totktonada]

I dived a bit further and it reminds me changes we did for msgpack-0.5.2.

We already use raw=False when encoding is 'utf-8' since msgpack-0.5.2 (2097884), because otherwise it emits the deprecation warning regarding encoding option usage. So we should just continue passing raw=False on msgpack-1.0.0.