Some library versions are outdated since the release of Debian Buster.

With this commit the required libraries versions will match as close as
possible the versions available in the current Debian stable release
(Buster).

Also, the requirements were tested against a Windows Python 3.7 to
ensure that a "pip install -r" can be used without the need of a CPP
compiler.

As Babel format_time now returns 'HNE' (Heure Normale de l'EST) for Fr
locale instead of the zone offset, the test is adapted.

Finally the babel.dates is explicitely imported, otherwise the proper
import of this submodule is relying on a side effect.

closes odoo/odoo#40361

Signed-off-by: Olivier Dony (odo) <odo@openerp.com>