[FIX] account_financial_report: KeyError rendering report

Some reports were failing to render without this fix.

It seems there was a regression introduced in 0a2b2736cd.

@moduon MT-8285

account_financial_report/report/general_ledger.py

@@ -863,6 +863,7 @@ class GeneralLedgerReport(models.AbstractModel):
             fin_bal_currency_ids = []
             fin_bal_currency_id = gl_item["currency_id"]
             if gl_item["currency_id"] or not foreign_currency:
+                gl_item["fin_bal_currency_id"] = fin_bal_currency_id
                 continue
             gl_item["fin_bal"]["bal_curr"] = gl_item["init_bal"]["bal_curr"]
             if "move_lines" in gl_item: