config: docker: Bump Python version for base template

This upgrade is inteded to make use of recent changes in handling
temporary files (in "tempfile" module).

Signed-off-by: Paweł Wieczorek <[email protected]>

Author: pawiecz

config/docker/base/python.jinja2

@@ -4,7 +4,7 @@
  # Author: Guillaume Tucker <[email protected]>
 -#}
 
-FROM mirror.gcr.io/python:3.11
+FROM mirror.gcr.io/python:3.12
 
 MAINTAINER "KernelCI TSC" <kernelci-tsc@groups.io>