feat: 升级JDK到21

leopard-core/src/main/java/com/lanyuanxiaoyao/leopard/core/entity/Stock.java

@@ -65,6 +65,19 @@ public class Stock extends SimpleEntity {
   @ToString.Exclude
   private Set<FinanceIndicator> indicators;
 
+  @Override
+  public boolean equals(Object o) {
+    if (o == null || getClass() != o.getClass()) return false;
+
+    Stock stock = (Stock) o;
+    return code.equals(stock.code);
+  }
+
+  @Override
+  public int hashCode() {
+    return code.hashCode();
+  }
+
   @Getter
   @AllArgsConstructor
   public enum Market implements SimpleEnum {