update ParallelIntegrationTest

Author: zhongkechen

sdk-integration-tests/src/test/java/software/amazon/lambda/durable/ParallelIntegrationTest.java

@@ -580,7 +580,7 @@ void testParallelWithMinSuccessful_earlyTermination() {
                     .completionConfig(CompletionConfig.minSuccessful(2))
                     .build();
             var futures = new ArrayList<DurableFuture<String>>();
-            var parallel = context.parallel("min-successful", config);
+            ParallelDurableFuture parallel = context.parallel("min-successful", config);
 
             try (parallel) {
                 for (var item : List.of("a", "b", "c", "d", "e")) {