refactor(website): update nextra

Author: Rel1cx

package.json

@@ -118,8 +118,6 @@
       "cross-spawn": "7.0.6",
       "is-core-module": "npm:@nolyfill/is-core-module@^1.0.39",
       "isarray": "npm:@nolyfill/isarray@^1.0.29",
-      "nextra": "3.1.0",
-      "nextra-theme-docs": "3.1.0",
       "safe-buffer": "npm:@nolyfill/safe-buffer@^1.0.41",
       "safer-buffer": "npm:@nolyfill/safer-buffer@^1.0.41",
       "side-channel": "npm:@nolyfill/side-channel@^1.0.29",