[Bug]: Testing SDK fails with ES modules: `__dirname is not defined`

[ZackKanter]

Expected Behavior

Expect that @aws/durable-execution-sdk-js-testing@1.0.0 would be compatible with ES modules.

Actual Behavior

Tests fail with:

  ReferenceError: __dirname is not defined
      at CheckpointWorkerManager.getWorkerPath

Steps to Reproduce

https://github.com/ZackKanter/durable-functions-bug-repro

SDK Version

1.0.0

Node.js Version

22.x

Is this a regression?

No

Last Working Version

No response

Additional Context

I may be missing something, as it seems that the library is intended to be compatible with ESM: #180