Update dependency hexo-generator-sitemap to v3

Author: renovate-bot

package.json

@@ -19,7 +19,7 @@
     "hexo-generator-category": "^1.0.0",
     "hexo-generator-index": "^1.0.0",
     "hexo-generator-searchdb": "^1.0.0",
-    "hexo-generator-sitemap": "^1.2.0",
+    "hexo-generator-sitemap": "3.0.1",
     "hexo-generator-tag": "^1.0.0",
     "hexo-related-popular-posts": "^3.0.0",
     "hexo-renderer-ejs": "^1.0.0",