[IMP] l10n_es_aeat_sii_oca: Replace line feeds by spaces in SII description

Although the field is now a single-line string, Odoo encodes line feeds
as `\n` when computing the SII description from the invoice lines, so
when sending that to the AEAT, they are not kept as is in the end.

On that cases, doing the SII match contrast, they will say there's no
exact match due to that.

Let's replace the line feeds by spaces in advance to avoid this problem.

Author: pedrobaeza

l10n_es_aeat_sii_oca/models/account_move.py

@@ -672,7 +672,7 @@ def _compute_sii_description(self):
                         "invoice_line_ids.ref"
                     )
                     names = [unidecode(x) for x in names if x]  # Avoid "ugly" chars
-                    description += " - ".join(filter(None, names))
+                    description += " - ".join(filter(None, names)).replace("\n", " ")
             invoice.sii_description = (description or "")[:500] or "/"
 
     @api.depends(