chore(deps): update dependency @promster/metrics to v15

Author: renovate[bot]

package-lock.json

@@ -77,7 +77,7 @@
     "syslog-portal": "dist/app.js"
   },
   "dependencies": {
-    "@promster/metrics": "^10.0.0",
+    "@promster/metrics": "^15.0.0",
     "@promster/server": "^14.0.0",
     "config": "^3.3.9",
     "es-main": "^1.2.0",