Bump prom-client from 11.5.3 to 15.1.2

Bumps [prom-client](https://github.com/siimon/prom-client) from 11.5.3 to 15.1.2.
- [Release notes](https://github.com/siimon/prom-client/releases)
- [Changelog](https://github.com/siimon/prom-client/blob/master/CHANGELOG.md)
- [Commits](siimon/prom-client@v11.5.3...v15.1.2)

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

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

Author: dependabot[bot]

package-lock.json

@@ -84,7 +84,7 @@
     "nav-frontend-typografi-style": "2.0.1",
     "openid-client": "4.2.2",
     "postcss-preset-env": "7.8.3",
-    "prom-client": "11.5.3",
+    "prom-client": "15.1.2",
     "react": "18.3.1",
     "react-collapse": "5.1.1",
     "react-document-title": "2.0.3",