add _pytest.mark to setup.py

Author: RonnyPfannschmidt

setup.py

@@ -75,7 +75,13 @@ def main():
         # the following should be enabled for release
         install_requires=install_requires,
         extras_require=extras_require,
-        packages=['_pytest', '_pytest.assertion', '_pytest._code', '_pytest.vendored_packages'],
+        packages=[
+            '_pytest',
+            '_pytest.assertion',
+            '_pytest._code',
+            '_pytest.vendored_packages',
+            '_pytest.mark',
+        ],
         py_modules=['pytest'],
         zip_safe=False,
     )