[TripGroupDelegate] Use plural handling for currencies

"Currencies: CAD" looks weird.

src/app/TripGroupDelegate.qml

@@ -106,7 +106,7 @@ Kirigami.AbstractCard {
 
         QQC2.Label {
             readonly property var currencies: TripGroupInfoProvider.currencies(tripGroup, Country.fromAlpha2(Settings.homeCountryIsoCode).currencyCode)
-            text: visible ? i18n("Currencies: %1", currencies.join(", ")) : ""
+            text: currencies.length > 0 ? i18np("Currency: %2", "Currencies: %2", currencies.length, currencies.join(", ")) : ""
             visible: currencies.length > 0
         }