Merge pull request #590 from tskit-dev/dependabot/pip/requirements/CI-tests-pip/pytest-xdist-2.4.0

Bump pytest-xdist from 2.3.0 to 2.4.0 in /requirements/CI-tests-pip

Author: mergify[bot]

requirements/CI-tests-pip/requirements.txt

@@ -6,7 +6,7 @@ matplotlib==3.4.3
 numpy==1.21.2
 pandas==1.2.5
 pytest==6.2.5
-pytest-xdist==2.3.0
+pytest-xdist==2.4.0
 seaborn==0.11.2
 sortedcontainers==2.4.0
 tqdm==4.62.3