Update pytest-xdist to 1.20.0

[pyup-bot]

There's a new version of pytest-xdist available.
You are currently using 1.19.1. I have updated it to 1.20.0

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

I couldn't find a changelog for this release. Do you know where I can find one? Tell me!

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

Happy merging! 🤖

[coveralls]

Coverage remained the same at 99.369% when pulling 2a3a9e4 on pyup-update-pytest-xdist-1.19.1-to-1.20.0 into a7e7360 on master.

[codecov]

Codecov Report

Merging #35 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #35   +/-   ##
=======================================
  Coverage   99.36%   99.36%           
=======================================
  Files          24       24           
  Lines        1109     1109           
=======================================
  Hits         1102     1102           
  Misses          7        7

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update a7e7360...2a3a9e4. Read the comment docs.