[FIX] account: Fix ensure_one method called on 'self' instead of 'st_line'

closes odoo/odoo#99633

Signed-off-by: Olivier Colson (oco) <oco@odoo.com>

addons/account/models/account_bank_statement.py

@@ -1011,7 +1011,7 @@ class AccountBankStatementLine(models.Model):
             company_currency = st_line.journal_id.company_id.currency_id
             journal_currency = st_line.journal_id.currency_id if st_line.journal_id.currency_id != company_currency else False
 
-            line_vals_list = self._prepare_move_line_default_vals()
+            line_vals_list = st_line._prepare_move_line_default_vals()
             line_ids_commands = [(1, liquidity_lines.id, line_vals_list[0])]
 
             if suspense_lines: