Update pytest-cov to 2.4.0

[pyup-bot]

There's a new version of pytest-cov available.
You are currently using 2.3.1. I have updated it to 2.4.0

These links might come in handy: PyPi | Changelog | Repo

Changelog

2.4.0

---

• Added a "disarm" option: --no-cov. It will disable coverage measurements. Contributed by Zoltan Kozma in
  PR135 <https://github.com/pytest-dev/pytest-cov/pull/135>_.

  WARNING: Do not put this in your configuration files, it's meant to be an one-off for situations where you want to
  disable coverage from command line.

• Fixed broken exception handling on .pth file. See 136 <https://github.com/pytest-dev/pytest-cov/issues/136>_.

Got merge conflicts? Close this PR and delete the branch. I'll create a new PR for you.

Happy merging! 🤖

[codecov-io]

Current coverage is 100% (diff: 100%)

Merging #17 into master will not change coverage

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