codecov package was removed from PyPI repository and tests on CI are failing.

[NoharaMasato]

Issue

Tests on CI(Github actions) are failing due to the installation failure of codecov package. e.g. https://github.com/jazzband/geojson/actions/runs/4710344620/jobs/8353921377

Cause

On 12th April 2023, codecov org removed codecov package from pypl repo which has been deprecated. https://about.codecov.io/blog/message-regarding-the-pypi-package/