I'm preparing to update bats to 1.11.0, but a change it includes will
require updating 3 of resholve's tests. Since a full resholve source
bump would need to go through staging now, I'm just patching the tests
in the separate test derivation.

Upcoming commit will add packages that use bats to passthru.tests,
which is a little more clear when this is one attrset.

Splitting this format-only change out for easier review.

It would have been ~easy for someone to update bats without noticing
whether the update broke any packages that depend directly on the
nixpkgs-packaged bats for their tests. (I'm phrasing this tediously
because there are also some packages that vendor a copy of bats.)

Hopefully this will make it easier to confirm future updates.

Also conditionally excludes pkill from resolution on macOS, since the
procps package should contain pkill on other platforms.