fix: bump docker machine version due to bug (#681)

This PR updates the docker+machine to the newest version. The fixed bug relevant here is:

With Docker 23.0.0 release (which happened today), installation of Docker doesn't create an /etc/docker directory
anymore by default. It needs to be done manually.
At the same time, Docker Machine's provisioning for some of the supported distributions assumes that it will be there by
default and starts writing key/certificates files into that directory immediately. Which fails with `ERROR: tee: /etc/docker/ca.pem: No such file or directory`

This fixes https://gitlab.com/gitlab-org/ci-cd/docker-machine/-/issues/98

variables.tf

@@ -116,7 +116,7 @@ variable "docker_machine_download_url" {
 variable "docker_machine_version" {
   description = "By default docker_machine_download_url is used to set the docker machine version. Version of docker-machine. The version will be ingored once `docker_machine_download_url` is set."
   type        = string
-  default     = "0.16.2-gitlab.15"
+  default     = "0.16.2-gitlab.19"
 }
 
 variable "runners_name" {