fix: backend/Dockerfile.tornado_api to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DEBIAN12-ZLIB-6008963
- https://snyk.io/vuln/SNYK-DEBIAN12-KRB5-6277411
- https://snyk.io/vuln/SNYK-DEBIAN12-NCURSES-6252773
- https://snyk.io/vuln/SNYK-DEBIAN12-SQLITE3-6155400
- https://snyk.io/vuln/SNYK-DEBIAN12-SYSTEMD-1560739

backend/Dockerfile.tornado_api

@@ -1,4 +1,4 @@
-FROM python:3.8-slim as builder
+FROM python:3.13.0b4-slim as builder
 
 ENV PYTHONDONTWRITEBYTECODE=1
 ENV PYTHONUNBUFFERED=1
@@ -22,7 +22,7 @@ RUN POETRY_VIRTUALENVS_CREATE=false poetry install --no-dev
 
 
 
-FROM python:3.8-slim as final
+FROM python:3.13.0b4-slim as final
 
 RUN DEBIAN_FRONTEND=noninteractive apt-get update && \
     apt-get install -y --no-install-recommends libpq-dev