每次跑gitlab ci都需要pull一个镜像很费时间，则可以修改gitlab-runner的参数

修改config.toml文件中的[[runners]] [runners.docker] pull_policy = “if-not-present”

[[runners]]
  [runners.docker]
    pull_policy = "if-not-present"

参考：

• https://docs.gitlab.com/runner/executors/docker.html#how-pull-policies-work
• https://stackoverflow.com/questions/63043714/gitlab-runner-pulls-image-for-every-job