Write unit tests for update OPA

[james-garriss]

💡 Summary

Convert the code in the run update opa workflow into functions and write unit tests for them.

Motivation and context

Unit tests are good.

Implementation notes

Please provide details for implementation, such as:

• Create function.
• Write Pester tests
• Test the tests.

Acceptance criteria

How do we know when this work is done?

• The functions have good tests.