Although the copilot bot integration is referred to by
`copilot-swe-agent[bot]`
(https://api.github.com/users/copilot-swe-agent[bot]), GitHub parses the
copilot identity as @\copilot in some cases, e.g.
https://github.com/zed-industries/zed/pull/44915#issuecomment-3657567754.
This causes the CLA check to still fail despite Copilot being added to
the CLA endpoint (and https://api.github.com/users/copilot returning a
404 for that very name..).

This PR fixes this by also considering the name alias of Copilot for the
`contributor` endpoint.

Release Notes:

- N/A