给version增加id字段，否则save方法不会覆盖记录而是新增

src/main/java/com/example/catchTheLetters/entity/Version.java

@@ -11,6 +11,10 @@ import java.io.Serializable;
  */
 @Data
 public class Version implements Serializable {
+    /**
+     * ID
+     */
+    private String id;
     /**
      * 数据表名称（即类名）
      */

src/test/java/com/example/catchTheLetters/TestInsertLevel.java

@@ -78,7 +78,7 @@ class TestInsertLevel {
             wordList.add(words.get(new Random().nextInt(words.size())));
         }
         // 时间全部设置为3分钟
-        var level = new Level("20", 20, "Level 20", type, 180000L, targetScore, wordList);
+        var level = new Level("21", 21, "Level 21", type, 180000L, targetScore, wordList);
 
         levelController.create(level);
     }