update(utc): 优化对 UTC Time 的序列化 review by melon

lib/utils.dart

@@ -2,5 +2,12 @@ import 'package:fis_common/extensions/date.dart';
 
 class JsonRpcUtils {
   static const String _datetimeFormat = "yyyy-MM-ddTHH:mm:ss.SSS";
-  static String dateFormat(DateTime date) => date.format(_datetimeFormat);
+  static const String _utcDateTimeFormat = "yyyy-MM-ddTHH:mm:ss.SSS'Z'";
+  static String dateFormat(DateTime date) {
+    if (date.isUtc) {
+      return date.format(_utcDateTimeFormat);
+    } else {
+      return date.format(_datetimeFormat);
+    }
+  }
 }