Bump prometheus-client from 0.9.0 to 0.11.0

Bumps [prometheus-client](https://github.com/prometheus/client_python) from 0.9.0 to 0.11.0.
- [Release notes](https://github.com/prometheus/client_python/releases)
- [Commits](prometheus/client_python@v0.9.0...v0.11.0)

---
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]

poetry.lock

@@ -15,7 +15,7 @@ flake8 = "3.9.0"
 flask = "1.1.2"
 Flask-Cors = "3.0.10"
 Flask-Migrate = "2.7.0"
-prometheus_client = "0.9.0"
+prometheus_client = "0.11.0"
 psycopg2-binary = "2.8.6"
 py-healthcheck = "1.10.1"
 pytest = "6.2.3"