fix: docker/Dockerfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-ALPINE319-OPENSSL-6593965
- https://snyk.io/vuln/SNYK-ALPINE319-OPENSSL-6593965

docker/Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3.9-alpine
+FROM python:3.13.0b1-alpine
 
 RUN addgroup -g 1234 -S synchro && adduser -u 1234 -G synchro -h /home/synchro -D synchro
 USER synchro