Fix flake8 in tests dir

[hackebrot]

This PR fixes all of the flake8 issues that I discovered while working on #480.

Once we got both merged, I will enable flake8 checks for the tests dir in addition to the cookiecutter package in tox.ini. 😤

cc @michaeljoseph

[codecov-io]

Current coverage is 95.64%

Merging #483 into master will not affect coverage as of 78a9e34

@@            master    #483   diff @@
======================================
  Files           12      12       
  Stmts          459     459       
  Branches         0       0       
  Methods          0       0       
======================================
  Hit            439     439       
  Partial          0       0       
  Missed          20      20       

Review entire Coverage Diff

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Uncovered Suggestions

1. +0.87% via cookiecutter/vcs.py#59...62
2. +0.66% via ...okiecutter/compat.py#78...80
3. +0.66% via ...okiecutter/compat.py#69...71
4. See 6 more...

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[michaeljoseph]

😸 👍