Don't compare years greater than as string

The date returned by `format('Y')` should be an integer which would make php change 2015 into an integer but it's a bit weird not to just do that ourselves.

Author: Kingdutch

modules/tax/src/Plugin/Commerce/TaxType/EuropeanUnionVat.php

@@ -66,7 +66,7 @@ protected function resolveZones(OrderItemInterface $order_item, ProfileInterface
     // to Germany needs to have German VAT applied.
     $taxable_type = $this->getTaxableType($order_item);
     $year = $this->getCalculationDate($order)->format('Y');
-    $is_digital = $taxable_type == TaxableType::DIGITAL_GOODS && $year >= '2015';
+    $is_digital = $taxable_type == TaxableType::DIGITAL_GOODS && $year >= 2015;
     $resolved_zones = [];
     if (empty($store_zones) && !empty($store_registration_zones)) {
       // The store is not in the EU but is registered to collect VAT.