restructuredtext-lint is not needed to run tests.

--- pytest-regressions-2.5.0/setup.py.orig
+++ pytest-regressions-2.5.0/setup.py
@@ -32,7 +32,6 @@
             "mypy",
             "numpy",
             "pillow",
-            "restructuredtext-lint",
             "tox",
         ],
         "num": [