fix: build/python-client/Dockerfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DEBIAN12-AOM-7197979
- https://snyk.io/vuln/SNYK-DEBIAN12-EXPAT-7855502
- https://snyk.io/vuln/SNYK-DEBIAN12-EXPAT-7855503
- https://snyk.io/vuln/SNYK-DEBIAN12-KRB5-7411315
- https://snyk.io/vuln/SNYK-DEBIAN12-KRB5-7411315

build/python-client/Dockerfile

@@ -1,5 +1,5 @@
 ARG PLATFORM=x86_64
-ARG BASE_IMAGE=python:3.8.18-bookworm
+ARG BASE_IMAGE=python:3.14.0a3-bookworm
 
 FROM --platform=$PLATFORM ${BASE_IMAGE}