`pulumi-terraform` tests fail on Pulumi v3.21.0

What happened?

I was migrating pulumi-terraform off of actions/upload-artifact@v2 and CI failed unexpectedly (unrelated to my change). Investigating showed that CI always fails now, though it succeeded on the last merge to master (3 months ago).

Pinning to v3.108.1 resolved the issue.

Example

Failed workflow: https://github.com/pulumi/pulumi-terraform/actions/runs/9688729320/job/26736002406

The workflow fails with:

  Diagnostics:
    terraform:state:RemoteStateReference (localstate):
      error: Diff is not yet implemented

My suspicion is that we have accidentally made Diff required instead of apply a default. This is a breaking change.

Passing workflow: https://github.com/pulumi/pulumi-terraform/actions/runs/9688978736/job/26736482099

Output of `pulumi about`

Additional context

Thread in slack: https://pulumi.slack.com/archives/C02VCJEBT2N/p1719449691127099

Contributing

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pulumi / pulumi