add missing prom-client to core

Author: nicktrn

packages/core/package.json

@@ -189,6 +189,7 @@
     "humanize-duration": "^3.27.3",
     "jose": "^5.4.0",
     "nanoid": "^3.3.4",
+    "prom-client": "^15.1.0",
     "socket.io": "4.7.4",
     "socket.io-client": "4.7.5",
     "std-env": "^3.8.1",