fix: backend-api/Dockerfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DEBIAN13-OPENSSL-15123186
- https://snyk.io/vuln/SNYK-DEBIAN13-OPENSSL-15123178
- https://snyk.io/vuln/SNYK-DEBIAN13-OPENSSL-15123183
- https://snyk.io/vuln/SNYK-DEBIAN13-OPENSSL-15123187
- https://snyk.io/vuln/SNYK-DEBIAN13-OPENSSL-15123204

Author: snyk-bot

backend-api/Dockerfile

@@ -1,5 +1,5 @@
 # Python backend Dockerfile
-FROM python:3.9-slim
+FROM python:3.14.3-slim
 
 # Set working directory
 WORKDIR /app