fix: install python3 if it is not present

mentioned in commit d839eec1

mentioned in merge request Orange-OpenSource/k8s-tz/tools/template-template!277 (merged)

mentioned in merge request Orange-OpenSource/lfn/ci_cd/chained-ci-client-launcher!297 (merged)

mentioned in merge request Orange-OpenSource/lfn/ci_cd/chained-ci-py!464 (merged)

mentioned in merge request Orange-OpenSource/lfn/ci_cd/docker-ansible-core!317 (merged)

mentioned in merge request Orange-OpenSource/lfn/infra/infra_collection!259 (merged)

mentioned in merge request Orange-OpenSource/lfn/infra/kubernetes_collection!331 (merged)

mentioned in merge request Orange-OpenSource/lfn/infra/os_infra_manager_docker!384 (merged)

mentioned in merge request Orange-OpenSource/lfn/infra/rke2_automatic_installation_collection!350 (merged)

mentioned in merge request arachnidsGrip/searchdown!69

mentioned in merge request to-be-contained/images!94

mentioned in merge request open-resources/docker/terraform-ansible!19 (merged)

mentioned in merge request hobyte/kube-cli!36

mentioned in merge request to-be-continuous/tools/gitlab-ci-test!8