MC-34360: [Paypal Express Checkout] Can't place an order if the currency is euro

- use base currency code

Author: krissyhiserote

app/code/Magento/Paypal/Model/SmartButtonConfig.php

@@ -131,7 +131,7 @@ private function generatePaypalSdkUrl(string $page): string
                 'merchant-id' => $this->config->getValue('merchant_id'),
                 'locale' => $this->localeResolver->getLocale(),
                 'intent' => $this->getIntent(),
-                'currency' => $this->storeManager->getStore()->getCurrentCurrencyCode(),
+                'currency' => $this->storeManager->getStore()->getBaseCurrencyCode(),
             ];
         if ($disallowedFunding) {
             $params['disable-funding'] = $disallowedFunding;

app/code/Magento/Paypal/Test/Unit/Model/SmartButtonConfigTest.php

@@ -61,7 +61,7 @@ protected function setUp(): void
 
         /** @var Store|MockObject $storeMock */
         $storeMock = $this->createMock(Store::class);
-        $storeMock->method('getCurrentCurrencyCode')
+        $storeMock->method('getBaseCurrencyCode')
             ->willReturn('USD');
 
         /** @var StoreManagerInterface|MockObject $storeManagerMock */