Fix broken test for api endpoint update

src/test/java/org/eclipsefoundation/mailing/resources/MailingListsResourceTests.java

@@ -17,7 +17,7 @@ import io.quarkus.test.junit.QuarkusTest;
 @TestInstance(Lifecycle.PER_CLASS)
 @QuarkusTest
 class MailingListsResourceTests {
-    public static final String MAILING_LISTS_BASE_URL = "/mailing-list";
+    public static final String MAILING_LISTS_BASE_URL = "/mailing_lists";
     public static final String AVAILABLE_MAILING_LISTS_URL = MAILING_LISTS_BASE_URL + "/available";
     public static final String MAILING_LISTS_BY_NAME_URL = MAILING_LISTS_BASE_URL + "/{listName}";