Update content.json

Signed-off-by: htj0301 <168163922+htj0301@users.noreply.github.com>

font/content.json

 {
     "to": "赵雨琦收",
-    "from": "听雨",
+    "from": "黄铁军^100<br>2024.05.01",
     "recipient": "赵雨琦同学",
-    "sender": "黄铁军 ^200<br>2024.05.01",
+    "sender": "听雨",
     "title": "Happy birthday!",
     "stamp": "./img/stamp.png",
     "bgm": "./bgm/bgm.mp3",