fix: correct country code for Persian locale and add corresponding test

Author: ThanosTsiamis

src/main/java/net/datafaker/providers/base/PhoneNumber.java

@@ -95,7 +95,7 @@ private static String detectCountryByLanguage(String language) {
             case "hy" -> "AM"; // Armenia
             case "uk" -> "UA"; // Ukraine
             case "ja" -> "JP"; // Japan
-            case "fa" -> "FR"; // France
+            case "fa" -> "IR"; // Iran
             case "ka" -> "GE"; // Georgia
             case "sq" -> "AL"; // Albania
             case "cs" -> "CZ"; // Czech Republic

src/test/java/net/datafaker/providers/base/PhoneNumberValidityFinderTest.java

@@ -46,6 +46,13 @@ void testValidNumber() throws NumberParseException {
         assertThat(util.isValidNumber(parsedNumber)).isTrue();
     }
 
+    @Test
+    void testLanguageOnlyPersianLocaleUsesIran() {
+        BaseFaker localFaker = new BaseFaker(new Locale("fa"));
+
+        assertThat(localFaker.phoneNumber().countryCodeIso2()).isEqualTo("IR");
+    }
+
     @ParameterizedTest
     @MethodSource("allSupportedLocales")
     void testAllPhoneNumbers(Locale supportedLocale) throws NumberParseException {