ci: add windows coverage

[alexeagle]

Fixes #97

[alexeagle]

Ugh! I can't reproduce this windows failure locally, even with
bazel clean --expunge; bazel --bazelrc=../../.github/workflows/ci.bazelrc --bazelrc=.bazelrc test --enable_bzlmod --noenable_runfiles //... --nocache_test_results
it is still green for me. That spot that passes the $(rlocation) for tarball.tar so the test failure isn't making sense. I'll come back to it later maybe.

[alexeagle]

@thesayyn this failure doesn't make sense to me from looking at the code, do you have any ideas?

[thesayyn]

@thesayyn this failure doesn't make sense to me from looking at the code, do you have any ideas?

it might repro if you delete docker.config at $HOME. Also it might help if you rebase as i am not sure if this branch was run against the main that has some fixes for docker config discovery.