[FIX] i18n: missing Slovenian translation

Slovenian language, as many others languages, is not present in the
beta/master projects in Transifex.

For some reason, Transiflex removed all current translations, this was
already fixed in 12, but as there are not automatic forward-port for
translations, this is a manual forward-port.

opw-2060055

closes odoo/odoo#36374

Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>