Make Fastlane Match work automatically with GitLab repo backends

Fastlane Match can use a private git repo as a storage backend for certificates and provisioning profiles. This is done by configuring Match to use a git_url in the Matchfile, for example: https://gitlab.com/gitlab-org/incubation-engineering/devops-for-mobile-apps/gitlab_unfiltered/-/blob/master/ios/fastlane/Matchfile

In the above example, I've added the CI_JOB_TOKEN to the URL so that Match is able to authenticate when it attempts to download the certificates. There should be a way to make the authentication automatic when using a GitLab git backend from a GitLab CI job.

This may already be possible based on the parameters built in to Match, or it could be made easier with a contribution to Fastlane. https://docs.fastlane.tools/actions/match/#parameters