Remove Saudi Arabia from the no postal code countries list (#770)

According to the following sources, Saudi Arabia uses
postal codes:
- https://address.gov.sa/en/address-format/overview
- https://en.wikipedia.org/wiki/List_of_postal_codes

Fixes #769

stripe/src/main/java/com/stripe/android/view/CountryUtils.java

@@ -12,14 +12,15 @@
 
 class CountryUtils {
 
-    static final String[] NO_POSTAL_CODE_COUNTRIES = {
+    private static final String[] NO_POSTAL_CODE_COUNTRIES = {
             "AE", "AG", "AN", "AO", "AW", "BF", "BI", "BJ", "BO", "BS", "BW", "BZ", "CD", "CF",
             "CG", "CI", "CK", "CM", "DJ", "DM", "ER", "FJ", "GD", "GH", "GM", "GN", "GQ", "GY",
             "HK", "IE", "JM", "KE", "KI", "KM", "KN", "KP", "LC", "ML", "MO", "MR", "MS", "MU",
-            "MW", "NR", "NU", "PA", "QA", "RW", "SA", "SB", "SC", "SL", "SO", "SR", "ST", "SY",
-            "TF", "TK", "TL", "TO", "TT", "TV", "TZ", "UG", "VU", "YE", "ZA", "ZW"};
-    static final Set<String> NO_POSTAL_CODE_COUNTRIES_SET = new HashSet<>(Arrays.asList
-            (NO_POSTAL_CODE_COUNTRIES));
+            "MW", "NR", "NU", "PA", "QA", "RW", "SB", "SC", "SL", "SO", "SR", "ST", "SY", "TF",
+            "TK", "TL", "TO", "TT", "TV", "TZ", "UG", "VU", "YE", "ZA", "ZW"
+    };
+    private static final Set<String> NO_POSTAL_CODE_COUNTRIES_SET = new HashSet<>(
+            Arrays.asList(NO_POSTAL_CODE_COUNTRIES));
 
     static boolean doesCountryUsePostalCode(@NonNull String countryCode) {
         return !NO_POSTAL_CODE_COUNTRIES_SET.contains(countryCode);
@@ -37,10 +38,11 @@ static boolean isUKPostcodeValid(@NonNull String postcode) {
         return Pattern.matches("^[A-Z]{1,2}[0-9R][0-9A-Z]? [0-9][ABD-HJLNP-UW-Z]{2}$", postcode);
     }
 
+    @NonNull
     static Map<String, String> getCountryNameToCodeMap() {
-        Map<String, String> displayNameToCountryCode = new HashMap<>();
+        final Map<String, String> displayNameToCountryCode = new HashMap<>();
         for (String countryCode : Locale.getISOCountries()) {
-            Locale locale = new Locale("", countryCode);
+            final Locale locale = new Locale("", countryCode);
             displayNameToCountryCode.put(locale.getDisplayCountry(), countryCode);
         }
         return displayNameToCountryCode;

stripe/src/test/java/com/stripe/android/view/CountryUtilsTest.java

@@ -1,16 +1,13 @@
 package com.stripe.android.view;
 
 import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.robolectric.RobolectricTestRunner;
 
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 /**
  * Test class for {@link CountryUtils}
  */
-@RunWith(RobolectricTestRunner.class)
 public class CountryUtilsTest {
 
     @Test