Bump prometheus-client from 0.17.1 to 0.21.1

Bumps [prometheus-client](https://github.com/prometheus/client_python) from 0.17.1 to 0.21.1.
- [Release notes](https://github.com/prometheus/client_python/releases)
- [Commits](prometheus/client_python@v0.17.1...v0.21.1)

---
updated-dependencies:
- dependency-name: prometheus-client
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

requirements.txt

@@ -40,5 +40,5 @@ cryptography==41.0.7
 requests[security]==2.31.0
 pymupdf==1.21.1
 
-prometheus-client==0.17.1
+prometheus-client==0.21.1
 sentry_sdk==2.0.1