Adding pip check to the CI

[benoit-cty]

Hi there!

I really enjoy OpenFisca, but I recently encountered an issue.

The deps of OpenFisca are strict. If we want to be sure that they are all aligned, it could be better to check it in CI.

I discover this issue when working on #1039 as it is a check done by the conda CI.

Here is what I did:

Run pip check

Here is what I expected to happen:

No broken requirements found.

Here is what actually happened:

flake8 3.9.2 has requirement pycodestyle<2.8.0,>=2.7.0, but you have pycodestyle 2.8.0.

According to pip show pycodestyle, pycodestyle was installed for : autopep8, flake8, flake8-print

Here is data (or links to it) that can help you reproduce this issue:

No data, just a fresh install done by:

python3 -m venv .venv
source .venv/bin/activate
pip install -U pip
pip install --editable .[dev] --use-deprecated=legacy-resolver

Context

I identify more as a:

• Developer (I create tools that use the existing OpenFisca code).