coverage action needs cleanup

[drammock]

The problems I see so far:

1. including coverage comment step in tests.yml breaks the publish workflow (as it's triggered on releases, not PRs, so there's no PR for it to write a comment to).

2. There's a dedicated workflow file for the coverage comment and also a step inside tests.yml that appears to do the same thing (though their configs are not identical):

pydata-sphinx-theme/.github/workflows/tests.yml

Lines 139 to 144 in 408c820

	- name: Coverage comment
	id: coverage_comment
	uses: py-cov-action/python-coverage-comment-action@v3
	with:
	GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
	MERGE_COVERAGE_FILES: true

These should be deduplicated.

3. IMO, ideally the release workflow wouldn't run coverage-related steps at all (only tests).

[trallard]

AFAIK this is already addressed by the last two CI PRs. So will close the issue but we can reopen if it turns this still needs work