[requires.io] dependency update

requires · requires · commit 6caea75ed236 · 2018-07-27T15:00:46.000+01:00
diff --git a/test_requirements.txt b/test_requirements.txt
@@ -1,4 +1,4 @@
 pytest==3.6.3
 pytest-cov==2.5.1
-pytest-xdist==1.22.3
+pytest-xdist==1.22.4
 hypothesis
