core: interface: remove unused collections

packages/hydrooj/package.json

@@ -63,7 +63,6 @@
         "@types/koa-router": "^7.4.4",
         "@types/koa-static-cache": "^5.1.1",
         "@types/lodash": "^4.14.184",
-        "@types/lru-cache": "^7.10.10",
         "@types/mime-types": "^2.1.1",
         "@types/minio": "^7.0.13",
         "@types/mongodb": "^3.6.20",