[REF] odoo-shippable: Use by default postgresql 9.6 instead of 9.3

• 9.3 is too old and odoo has errors related with older PostgreSQL versions
  • Similar to https://github.com/OCA/maintainer-quality-tools/issues/432#issuecomment-281580935
• PostgreSQL 9.3 is not supporting 'max_wal_size' configuration parameter.
  • It parameter is required to configure a non-durability PostgreSQL More info about: https://www.postgresql.org/docs/10/static/non-durability.html
• PostgreSQL 9.3 is not supporting INSERT INTO ... ON CONFLICT DO NOTHING

Fix https://github.com/Vauxoo/docker-odoo-image/issues/315