defaults: Update the base image to use Git 2.45
The base image is using Git 2.36, which is around 2 years old. Let's update the base image to use Git 2.45. This is a follow up after updating the gitlab-build-images repository 'b69ef95 (git: Update Git version from 2.33/2.36 to 2.45, 2024-07-29)'.