Cannot allow self signed certificates with current `httpClient` access level

[DavidBrunow]

I'm using this library with an internal GitLab enterprise instance that is using a self-signed certificate. Without adjusting the access level of the GLApis httpClient to public I cannot set the security on that client to .acceptSelfSigned. Here is where I make that change for our use: https://github.com/malcommac/GitLabSwift/blob/main/Sources/GitLabSwift/Core/GLApi.swift#L76

I don't think that the best answer is to make that httpClient public but some way to influence the security would be nice.