Prerequisite Terraform setup script points to latest instead of required

[andrewDoing]

Describe the bug:
Running setup_terraform.sh installs the latest version of terraform (0.13.3), which isn't compatible with Bedrock according to the README and cluster/common/provider/main.tf

To Reproduce:
Run the tools/prereqs/setup_terraform.sh script.
Run terraform -version

Expected behavior:
Installs the required version of terraform.

Additional context:
The script should look at one location in the repo to determine the version of Terraform it should download.

Does this require updates to documentation?:
No

[andrebriggs]

Looks like Terraform 13 is very recent. @andrewDoing you should download Terraform 12 instead to unblock yourself for now.

This probably could be solved with Docker images like the PR #1407 or Bedrock agents

Will prioritize this. cc @jmspring