Allow neutral status

[lazytesting]

I'm using this in combination with Azure Devops checks and they report a neutral state back when they are skipped due to path exclusion.

It would be nice if the 'neutral' conclusion state would be marked as success.

There are two ways to do this:

1. add 'neutral' to this line
2. make the acceptable conclusions configurable with a default of 'skipped' and 'success'

Happy to contribute with a PR.

[cam-bond]

CodeQL also reports back a neutral status. This should be allowed IMO

[eirnym]

Current PR is #445

[eirnym]

@dghubble Here's official documentation which confirms the requirement to list at least neutral status as "non-negative" and don't fail on it.