Fix error prometheus gauge metrics_azurerm_reservation.go (#99)

* Update metrics_azurerm_reservation.go

Fix error prometheus gauge, attempt 5, actual 6

* Update metrics_azurerm_reservation.go

---------

Co-authored-by: Markus Blaschke <mblaschke82@gmail.com>

Author: PaulPowershell

metrics_azurerm_reservation.go

@@ -30,6 +30,7 @@ func (m *MetricsCollectorAzureRmReservation) Setup(collector *collector.Collecto
 	m.Processor.Setup(collector)
 
 	commonLabels := []string{
+		"scope",
 		"reservationOrderID",
 		"reservationID",
 		"skuName",