Changes to Terraform versions and data values

This MR gets the example Gitlab Terraform EKS repo into a working state. It uses aspects of current pending MRs but I hope merging this in gives us a stable base to keep improving upon this solution.

(First MR so forgive me for any administrative/workflow oversight)

Terraform providers updated to the latest version. EKS provider updated to the latest version.

As mentioned in issue #17

name = module.eks.cluster_id was changed to name = module.eks.cluster_name id is for AWS Outposts only so changing to cluster_name resolves issues here.

As mentioned here - !9 (comment 1510241082)

The GitLab agent fails as it doesn't get the Cluster endpoint. Adding a depends on to this data item forces terraform to wait for EKS to finish deploying first. depends_on = [module.eks.cluster_name]

When deploying this out of the box users may find the solution to fail as EKS is setup in its own VPC. Adding extra documentation covering the networking aspects of EKS would improve upon this.

In my testing I made the API endpoint public for testing purposes and the Terraform was completed successfully.