codecov is being flakey (again)

[grahamgower]

E.g. see https://github.com/popsim-consortium/demes-python/pull/320/checks?check_run_id=2763665184.

ErrorDetail(string='Unable to locate build via Github Actions API. Please upload with the Codecov repository upload token to resolve issue.', code='not_found')

From my previous investigations, this turned out to be a rate-limiting problem with codecov being denied access to the github API. The previously proposed fix was to either use a codecov access token (supposedly not required for public projects) or to install the codecov marketplace app (which has been done, and is supposedly not required for public projects anyhow).

[grahamgower]

This seems to have settled down after some upstream codecov action changes.
codecov/codecov-action#330