qml: qeinvoice: fix regression in update_userinfo

follow-up 3b0cdef871

```
 29.60 | E | lnworker.LNWallet.[test_segwit_2] | Exception in pay_invoice: TypeError("unhashable type: 'list'")
Traceback (most recent call last):
  File "/home/user/wspace/electrum/electrum/util.py", line 1153, in wrapper
    return await func(*args, **kwargs)
  File "/home/user/wspace/electrum/electrum/lnworker.py", line 1518, in pay_invoice
    self.set_invoice_status(key, PR_INFLIGHT)
  File "/home/user/wspace/electrum/electrum/lnworker.py", line 2404, in set_invoice_status
    util.trigger_callback('invoice_status', self.wallet, key, status)
  File "/home/user/wspace/electrum/electrum/util.py", line 1796, in trigger_callback
    callback(*args)
  File "/home/user/wspace/electrum/electrum/gui/qml/qeinvoice.py", line 90, in on_event_invoice_status
    self.update_userinfo()
  File "/home/user/wspace/electrum/electrum/gui/qml/qeinvoice.py", line 327, in update_userinfo
    self.userinfo = userinfo_for_invoice_status([self.status])
  File "/home/user/wspace/electrum/electrum/gui/qml/qeinvoice.py", line 305, in userinfo_for_invoice_status
    return {
TypeError: unhashable type: 'list'
```

electrum/gui/qml/qeinvoice.py

@@ -301,7 +301,7 @@ class QEInvoice(QObject, QtEventListener):
         if amount.isEmpty and self.status == PR_UNPAID:  # unspecified amount
             return
 
-        def userinfo_for_invoice_status(status):
+        def userinfo_for_invoice_status(status: int) -> str:
             return {
                 PR_EXPIRED: _('This invoice has expired'),
                 PR_PAID: _('This invoice was already paid'),
@@ -324,13 +324,13 @@ class QEInvoice(QObject, QtEventListener):
                     # TODO: subtract fee?
                     self.userinfo = _('Insufficient balance')
             else:
-                self.userinfo = userinfo_for_invoice_status([self.status])
+                self.userinfo = userinfo_for_invoice_status(self.status)
         elif self.invoiceType == QEInvoice.Type.OnchainInvoice:
             if self.status in [PR_UNPAID, PR_FAILED]:
                 if not ((amount.isMax and self.get_max_spendable_onchain() > 0) or (self.get_max_spendable_onchain() >= amount.satsInt)):
                     self.userinfo = _('Insufficient balance')
             else:
-                self.userinfo = userinfo_for_invoice_status([self.status])
+                self.userinfo = userinfo_for_invoice_status(self.status)
 
     def determine_can_pay(self):
         self.canPay = False