[ldapfeed] re-enable ldap tests for python 3.7
This was disabled because ldap3<2 wasn't compatible with python 3.7
While I'm here, drop unseless newline.
[main]
cubicweb.session.secret = %(secret_1)s
cubicweb.auth.authtkt.session.secret = %(secret_2)s
cubicweb.auth.authtkt.persistent.secret = %(secret_3)s
cubicweb.auth.authtkt.session.secure = no
cubicweb.auth.authtkt.persistent.secure = no