Testing expects pytest-xdist.

--- pytest_benchmark-5.3.0/tox.ini.orig
+++ pytest_benchmark-5.3.0/tox.ini
@@ -45,7 +45,7 @@
     pytest90: pytest==9.0.3
     pytest91: pytest==9.1.1
     setuptools>=80
-    xdist: pytest-xdist==3.8.0
+    pytest-xdist==3.8.0
 commands =
     {posargs:pytest -vv --ignore=src}
     cover: {posargs:pytest --cov --cov-report=term-missing --cov-report=xml -vv}