Pin pytest to 5.3.3 to test fix

Author: SalmonMode

setup.py

@@ -31,7 +31,7 @@ def read(fname):
     python_requires='>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*',
     setup_requires=['setuptools_scm>=1.11.1'],
     install_requires=[
-        'pytest>=3.6',
+        'pytest==5.3.3',
         'pathlib2;python_version<"3.4"',
     ],
     extras_require={