refactor(flow-task): 使用collect(Collectors.toList())替换toList()方法

refactor(flow-engine): 在`AssignUserFormStrategyImpl`中添加`Collectors`导入并使用`collect(Collectors.toList())`替换`toList()`方法

本次提交主要将Java 16引入的`toList()`方法替换为`collect(Collectors.toList())`，以确保代码在更低版本的Java环境中兼容。

pigx-flow/pigx-flow-engine/pigx-flow-engine-biz/src/main/java/com/pig4cloud/pigx/flow/engine/node/impl/AssignUserFormStrategyImpl.java

@@ -14,6 +14,7 @@ import org.springframework.stereotype.Component;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.stream.Collectors;
 
 /**
  * 来自表单
@@ -37,7 +38,7 @@ public class AssignUserFormStrategyImpl implements AssignUserStrategy {
 		if (variable != null && !StrUtil.isBlankIfStr(variable)) {
 			String jsonString = objectMapper.writeValueAsString(variable);
 			List<NodeUser> nodeUserDtoList = JSONUtil.toList(jsonString, NodeUser.class);
-            assignList.addAll(nodeUserDtoList.stream().map(NodeUser::getId).toList());
+            assignList.addAll(nodeUserDtoList.stream().map(NodeUser::getId).collect(Collectors.toList()));
 		}
 
 		return assignList;

pigx-flow/pigx-flow-task/pigx-flow-task-biz/src/main/java/com/pig4cloud/pigx/flow/task/service/impl/RemoteServiceImpl.java

@@ -134,7 +134,7 @@ public class RemoteServiceImpl implements IRemoteService {
                 .getData()
                 .stream()
                 .map(SysUser::getUserId)
-                .toList();
+                .collect(Collectors.toList());
 		return R.ok(list);
 	}