build: use prepare+build

packages/hydrooj/package.json

@@ -26,7 +26,7 @@
         "koa-router": "^10.0.0",
         "koa-static-cache": "^5.1.3",
         "lodash": "^4.17.21",
-        "minio": "7.0.18",
+        "minio": "7.0.17",
         "moment-timezone": "^0.5.32",
         "mongodb": "^3.6.6",
         "nodemailer": "^6.5.0",