[FIX] base_import: datetime patterns
[FIX] base_import: datetime patterns

Turns out %s is not the pattern for sub-minute seconds, that'd be
%S (note the casing). The former is the number of seconds since
epoch, which tends not to match sub-minute second patterns (sounds
like bull to me but there you are), and so importing datetimes was a
bit broken since the previous improvements.

Fix that.

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo