core: fix load

packages/hydrooj/package.json

@@ -1,6 +1,6 @@
 {
     "name": "hydrooj",
-    "version": "2.20.19",
+    "version": "2.20.20",
     "bin": "bin/hydrooj.js",
     "main": "dist/loader.js",
     "typings": "dist/loader.d.ts",

packages/hydrooj/src/entry/common.ts

@@ -30,7 +30,7 @@ export const builtinHandler = [
 ];
 
 export const builtinScript = [
-    'rating', 'difficulty', 'problemStat', 'blacklist', 'deleteUser',
+    'rating', 'problemStat', 'blacklist', 'deleteUser',
 ];
 
 function getFiles(folder: string, base = ''): string[] {