KOP-3126 itcase: Use xta-test-server w/o NCName restriction

src/test/java/de/ozgcloud/xta/client/extension/XtaTestServerSetupExtension.java

@@ -24,7 +24,7 @@ import lombok.extern.slf4j.Slf4j;
 public class XtaTestServerSetupExtension implements BeforeAllCallback, AfterAllCallback {
 
 	private static final DockerImageName XTA_TEST_SERVER_IMAGE = DockerImageName.parse("docker.ozg-sh.de/xta-test-server")
-			.withTag("latest");
+			.withTag("1.9.0-MR-6");
 
 	private static final String XTA_TEST_CLIENT_KEYSTORE_PATH = "store/xta-test-client-john-smith_keystore.p12";
 	private static final String XTA_TEST_CLIENT_KEYSTORE_PASSWORD = "password";