CI: Set pytest minversion to 4.0.2

Author: simonjayhawkins

setup.cfg

@@ -57,6 +57,7 @@ split_penalty_after_opening_bracket = 1000000
 split_penalty_logical_operator = 30
 
 [tool:pytest]
+minversion = 4.0.2
 testpaths = pandas
 markers =
  single: mark a test as single cpu only