fix hexo version to 7.3.0 to be compatible with hexo-ai-summary-liushen plugin

package.json

@@ -9,13 +9,13 @@
     "server": "hexo server"
   },
   "hexo": {
-    "version": "8.0.0"
+    "version": "7.3.0"
   },
   "dependencies": {
     "@sveltia/cms": "^0.109.0",
     "axios": "^1.12.2",
     "cheerio": "^1.1.2",
-    "hexo": "^8.0.0",
+    "hexo": "^7.3.0",
     "hexo-abbrlink": "^2.2.1",
     "hexo-ai-summary-liushen": "^1.3.0",
     "hexo-deployer-git": "^4.0.0",