pyarrow is not needed to run tests.

--- pytest_regressions-2.6.0/setup.py.orig
+++ pytest_regressions-2.6.0/setup.py
@@ -33,7 +33,6 @@
             "mypy",
             "numpy",
             "pillow",
-            "pyarrow",
             "tox",
         ],
         "num": [