Potential dependency conflicts between python-weixin and chardet

[NeolithEra]

Hi, as shown in the following full dependency graph of python-weixin, python-weixin requires chardet (the latest version), while the installed version of requests(2.22.0) requires chardet>=3.0.2,<3.1.0.

According to Pip's “first found wins” installation strategy, chardet 3.0.4 is the actually installed version.

Although the first found package version chardet 3.0.4 just satisfies the later dependency constraint (chardet>=3.0.2,<3.1.0), it will lead to a build failure once developers release a newer version of chardet in the near future, which is greater than 3.1.0.

Dependency tree--------

python-weixin(version range:)
| +-simplejson(version range:)
| +-requests(version range:)
| | +-chardet(version range:>=3.0.2,<3.1.0)
| | +-idna(version range:>=2.5,<2.9)
| | +-urllib3(version range:>=1.21.1,<1.26)
| | +-certifi(version range:>=2017.4.17)
| +-chardet(version range:)
| +-six(version range:)
| +-xmltodict(version range:)
| +-pycryptodome(version range:)```

Thanks for your attention.
Best,
Neolith

[NeolithEra]

Solution

1. Fix your direct dependencies to be chardet>=3.0.2,<3.1.0 and requests==2.22.0, to remove this conflict.
   I have checked this revision will not affect your downstream projects now.
2. Remove your direct dependency chardet, and use the library chardet(>=3.0.2,<3.1.0) transitively introduced by requests.

Personally, I prefer solution 2.
What's your opinion?

@#1gusibi May I pull a request to solve this issue?