build: 更新版本号至 3.0.0

- 将 package.json 中的版本号从 2.1.16 修改为 3.0.0
- 此次更新标志着主题进行了重大升级，提升了功能和性能

package.json

@@ -1,6 +1,6 @@
 {
   "name": "hexo-theme-solitude",
-  "version": "2.1.16",
+  "version": "3.0.0",
   "description": "A beautiful, powerful, and efficient Hexo theme developed by everfu.",
   "main": "package.json",
   "scripts": {