fix: pin pytest-xdist to avoid release failures (#2896)

Author: mufaddal-rohawala

setup.py

@@ -68,7 +68,7 @@ def read_version():
         "pytest-cov",
         "pytest-rerunfailures",
         "pytest-timeout",
-        "pytest-xdist",
+        "pytest-xdist==2.4.0",
         "coverage<6.2",
         "mock",
         "contextlib2",