fix: Dockerfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DEBIAN11-DPKG-2847942
- https://snyk.io/vuln/SNYK-DEBIAN11-LIBTASN16-3061097
- https://snyk.io/vuln/SNYK-DEBIAN11-OPENSSL-2807596
- https://snyk.io/vuln/SNYK-DEBIAN11-OPENSSL-2933518
- https://snyk.io/vuln/SNYK-DEBIAN11-OPENSSL-3314584

Dockerfile

@@ -10,7 +10,7 @@ COPY cozify_exporter ./cozify_exporter
 COPY poetry.lock pyproject.toml ./
 RUN poetry build -f wheel
 
-FROM python:3.11.0a6-slim-bullseye
+FROM python:3.12.0b3-slim-bullseye
 WORKDIR /srv
 COPY --from=builder /build/dist/*.whl ./
 RUN pip install *.whl