fix upgrade command to look for nebari_version instead of qhub_version

[Adam-D-Lewis]

Reference Issues or PRs

What does this implement/fix?

The nebari upgrade command ran all the upgrade steps every time if your nebari-config.yaml had nebari_version since it was still expecting qhub_version. I'm fixing that here.
Put a x in the boxes that apply

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds a feature)
• Breaking change (fix or feature that would cause existing features not to work as expected)
• Documentation Update
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build related changes
• Other (please describe):

Testing

• Did you test the pull request locally?
• Did you add new tests?

Any other comments?

[iameskild]

Thanks @Adam-D-Lewis :)

[kcpevey]

FYI - The k8s test is failing on other PRs as well. I dont know why since nothing has changed to cause that failure. Maybe its downstream dependency change?

[Adam-D-Lewis]

@kcpevey Yeah, it certainly isn't anything in this PR. Not sure the root cause either, but I agree a dependency change seems most likely.