Sign Release Step Failing - Preventing New Versions from Going to PyPi

**Describe the bug**
The Sign Release step on the Release job in actions is failing. The error is below along with a link to the failed job.

`signing failed: No secret key`

https://github.com/aws/sagemaker-experiments/actions/runs/3016953615/jobs/4850337703

Looks like the latest version to make it to PyPi is 0.1.35. The latest release on the project is 0.1.39.

https://github.com/aws/sagemaker-experiments/releases
https://pypi.org/project/sagemaker-experiments/#history

**To Reproduce**

See Link
https://github.com/aws/sagemaker-experiments/actions/runs/3016953615/jobs/4850337703

**Expected behavior**
The release stage completes all steps including pushing to PyPi

**Screenshots**
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**Environment:**
Framework (e.g. TensorFlow) / Algorithm (e.g. KMeans):
Framework Version:
Python Version:
CPU or GPU:
Python SDK Version:
Are you using a custom image:

**Additional context**
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