Update to use capabilities queries

[robindevitt]

WP 5.9 includes new capabilities user queries that replace the role based who query parameter.

This PR includes the capabilities query.

Issue #523

[robindevitt]

@shadyvb & @roborourke, I have noticed that all the checks have failed. Should I review each and fix appropriately? From what I have seen they don't appear to be directly related to the code changes made, a few are falling at "Install PHP Dependencies".

[shadyvb]

The changes seem fine, apart from lock files.

• I can see composer lock file includes more changes that might not be needed ( eg: coding standards version update ), so wondering how the WordPress update was carried out.
• Is the packages lock file update expected ? seems like quite a bit of changes.

Also, do we need to update the reference at https://github.com/humanmade/authorship/blob/develop/.github/workflows/test.yml#L17 ?

Also we do need to fix the CI before merging. I can see it's the composer version that might need to be updated.

[robindevitt]

Hey @shadyvb

Thanks for the review and direction (slack thread).

I have updated the PR.

I have one check failing, is this the same as what you referenced in your review earlier?