Use the Codecov CLI to upload coverage

[matthewfeickert]

Summary

To potentially use Sentry's/Codecov's ATS we first need to use the Codecov CLI to upload our coverage reports.

https://docs.codecov.com/docs/the-codecov-cli#how-to-upload-to-codecov makes it seem like the workflow would be

$ python -m pip install --upgrade codecov-cli
$ codecovcli create-commit
$ codecovcli create-report
$ codecovcli do-upload

though I'm not sure how to replace all the options we use with the codecov-action

pyhf/.github/workflows/ci.yml

Lines 64 to 72 in fb604e8

	# Report coverage for oldest and newest Python tested to deal with version differences
	- name: Report core project coverage with Codecov
	if: >-
	github.event_name != 'schedule' &&
	matrix.os == 'ubuntu-latest'
	uses: codecov/codecov-action@v3
	with:
	files: ./coverage.xml
	flags: unittests-${{ matrix.python-version }}

Additional Information

CLI Options: https://docs.codecov.com/docs/cli-options

Code of Conduct

• I agree to follow the Code of Conduct

[matthewfeickert]

Given https://docs.codecov.com/docs/cli-options this might be doable with just

$ python -m pip install --upgrade codecov-cli
$ codecovcli create-commit
$ codecovcli create-report
$ codecovcli do-upload --file ./coverage.xml --flag unittests-${{ matrix.python-version }}