.gitlab-ci.yml: use Debian 12-based container image with curl / tar 1.35

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

.gitlab-ci.yml

@@ -1,7 +1,7 @@
 # Configuration for Gitlab-CI.
 # Builds appear on https://gitlab.com/buildroot.org/buildroot/pipelines
 
-image: $CI_REGISTRY/buildroot.org/buildroot/base:20230207.1123
+image: $CI_REGISTRY/buildroot.org/buildroot/base:20250205.1514
 
 stages:
   - generate-gitlab-ci