fix:

编码策略bug修复

tr-plugins/tr-spring-boot-starter-plugin-numbering-strategy/src/main/java/cn/tr/plugin/numbering/strategy/core/annotation/Numbering.java

@@ -22,5 +22,5 @@ public @interface Numbering {
      * 编号策略编码
      */
     @AliasFor("value")
-    String code();
+    String code() default "";
 }