add latest pytest version

Author: TvoroG

tox.ini

@@ -53,7 +53,7 @@ deps =
      pytest_5_2: pytest<5.3.0
      pytest_5_2: attrs==19.1.0
 
-     pytest_5_3: pytest==5.3.0
+     pytest_5_3: pytest<5.4.0
      pytest_5_3: attrs==19.1.0
 
      numpy==1.16.5