Double % to define log_format and log_date_format in setup.cfg (cf. pytest-dev/pytest#3062)

Author: brenard31

setup.cfg

@@ -28,5 +28,5 @@ test = pytest
 
 [tool:pytest]
 addopts = --ignore=setup.py
-log_format = %(asctime)s %(levelname)s %(message)s
-log_date_format = %Y-%m-%d %H:%M:%S
+log_format = %%(asctime)s %%(levelname)s %%(message)s
+log_date_format = %%Y-%%m-%%d %%H:%%M:%%S