code coverage on PRs does not seem to be working

the code cov estimates on https://github.com/sourmash-bio/sourmash/pull/3072 are clearly wrong, and this popped up elsewhere too - https://github.com/sourmash-bio/sourmash/pull/3066#issuecomment-1986880433

maybe we need to pay attention to https://github.com/sourmash-bio/sourmash/pull/2980?