Exclude untestable code from coverage

[sanders41]

Closes #

Code Changes

• Added pragma: no cover to if __name__ == "__main__:" code
• Excluded migrations from coverage

Steps to Confirm

• Run pytest tests/ctl -m "unit" and verify migrations and if __name__ == "__main__:" sections are not included in the term-missing section

Pre-Merge Checklist

• All CI Pipelines Succeeded
• Documentation:
  • documentation complete, PR opened in fidesdocs
  • documentation issue created in fidesdocs
• Issue Requirements are Met
• Relevant Follow-Up Issues Created
• Update CHANGELOG.md

Description Of Changes

In thinking about #2135 I am adding some exclusions from coverage here. The migrations are used by alembic and not by fides code directly, the only reason we have them in a directory under coverage is so plus can access them.

We could probably jump through some hoops and find a way to test the if __name__ == "__main__:" sections, but doing so would be for the sake of coverage and not meaningful.

[ThomasLaPiana]

Thanks for this!