submodule对gitea不管用，所以直接拉了一份拉格兰

Lagrange.Core/Lagrange.OneBot/Core/Entity/OneBotGroupNotice.cs

@@ -0,0 +1,33 @@
+using System.Text.Json.Serialization;
+
+namespace Lagrange.OneBot.Core.Entity;
+
+[Serializable]
+public class OneBotGroupNoticeImage(string id, string height, string width)
+{
+    [JsonPropertyName("id")] public string Id { get; set; } = id;
+
+    [JsonPropertyName("height")] public string Height { get; set; } = height;
+
+    [JsonPropertyName("width")] public string Width { get; set; } = width;
+}
+
+[Serializable]
+public class OneBotGroupNoticeMessage(string text, IEnumerable<OneBotGroupNoticeImage> images)
+{
+    [JsonPropertyName("text")] public string Text { get; set; } = text;
+
+    [JsonPropertyName("images")] public IEnumerable<OneBotGroupNoticeImage> Images { get; set; } = images;
+}
+
+[Serializable]
+public class OneBotGroupNotice(string noticeId, long senderId, long publishTime, OneBotGroupNoticeMessage message)
+{
+    [JsonPropertyName("notice_id")] public string NoticeId { get; set; } = noticeId;
+
+    [JsonPropertyName("sender_id")] public long SenderId { get; set; } = senderId;
+
+    [JsonPropertyName("publish_time")] public long PublishTime { get; set; } = publishTime;
+
+    [JsonPropertyName("message")] public OneBotGroupNoticeMessage Message { get; set; } = message;
+}