build(deps): bump prom-client from 14.2.0 to 15.1.1

Bumps [prom-client](https://github.com/siimon/prom-client) from 14.2.0 to 15.1.1.
- [Release notes](https://github.com/siimon/prom-client/releases)
- [Changelog](https://github.com/siimon/prom-client/blob/master/CHANGELOG.md)
- [Commits](siimon/prom-client@v14.2.0...v15.1.1)

---
updated-dependencies:
- dependency-name: prom-client
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

package.json

@@ -11,7 +11,7 @@
   "dependencies": {
     "commander": "~7.2",
     "http-proxy": "^1.18.1",
-    "prom-client": "14.2.0",
+    "prom-client": "15.1.1",
     "strftime": "~0.10.0",
     "winston": "~3.13.0"
   },