Revise urllib3’s version constraint to remove the potential dependency conflicts

[NeolithEra]

Hi, as shown in the following full dependency graph of Machine-Learning-with-Python, Machine-Learning-with-Python requires urllib3 (the latest version)， while the installed version of requests(2.22.0) requires urllib3>=1.21.1,<1.26.

According to pip's “first found wins” installation strategy, urllib3 1.25.3 is the actually installed version.

Although the first found package version urllib3 1.25.3 just satisfies the later dependency constraint （urllib3>=1.21.1,<1.26), it will lead to a build failure once developers release a newer version of urllib3.

Dependency tree--------

Machine-Learning-with-Python(version range:)
| +-asn1crypto(version range:==0.24.0)
| +-backcall(version range:==0.1.0)
| +-beautifulsoup4(version range:==4.6.3)
| +-certifi(version range:==2018.8.24)
| +-cffi(version range:==1.11.5)
| +-chardet(version range:==3.0.4)
| +-cryptography(version range:==2.3.1)
| +-cycler(version range:==0.10.0)
| +-h5py(version range:==2.9.0)
| | +-numpy(version range:>=1.7)
| | +-six(version range:)
| +-idna(version range:==2.7)
| +-inflection(version range:==0.3.1)
| +-ipython(version range:==7.2.0)
| +-jedi(version range:==0.13.2)
| +-keras(version range:==2.2.4)
| | +-numpy(version range:>=1.9.1)
| | +-scipy(version range:>=0.14)
| | +-six(version range:>=1.9.0)
| | +-pyyaml(version range:)
| | +-h5py(version range:)
| | | +-numpy(version range:>=1.7)
| | | +-six(version range:)
| | +-keras_applications(version range:>=1.0.6)
| | +-keras_preprocessing(version range:>=1.0.5)
| +-keras-preprocessing(version range:==1.0.5)
| +-kiwisolver(version range:==1.0.1)
| +-matplotlib(version range:==3.0.0)
| +-more-itertools(version range:==5.0.0)
| +-numpy(version range:==1.15.2)
| +-pandas(version range:==0.23.4)
| +-patsy(version range:==0.5.0)
| +-pexpect(version range:==4.6.0)
| +-pickleshare(version range:==0.7.5)
| +-pip(version range:==10.0.1)
| +-ptyprocess(version range:==0.6.0)
| +-pycparser(version range:==2.19)
| +-pygments(version range:==2.3.1)
| +-pyopenssl(version range:==18.0.0)
| +-pyparsing(version range:==2.2.1)
| +-pysocks(version range:==1.6.8)
| +-python-dateutil(version range:==2.7.3)
| +-pytz(version range:==2018.5)
| +-quandl(version range:==3.4.5)
| +-requests(version range:>=2.20.0)
| | +-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)
| +-scikit-learn(version range:==0.20.0)
| +-scipy(version range:==1.1.0)
| +-seaborn(version range:==0.9.0)
| +-setuptools(version range:==40.2.0)
| +-six(version range:==1.11.0)
| +-statsmodels(version range:==0.9.0)
| +-tornado(version range:==5.1.1)
| +-traitlets(version range:==4.3.2)
| +-urllib3(version range:>=1.24.2)
| +-wcwidth(version range:==0.1.7)
| +-wheel(version range:==0.31.1)

Thanks for your attention.
Best,
Neolith

[NeolithEra]

Solution

1. Fix your direct dependencies to be urllib3>=1.21.1,<1.26 and requests==2.22.0, to remove this conflict.

2. Remove your direct dependency urllib3, and use urllib3 transitively introduced by request.

@devAmoghS Please let me know your choice. I can submit a PR to solve this issue.
Build a good dependency ecosystem for python projects is our common goal ^_^.

[devAmoghS]

@NeolithEra Thank you for raising the issue. Please go ahead with making the PR. Will merge it after the review. We need more contributors for this project!!