so we will be able to drop Python 3.7 support for the rest of the code base.
Add a new `test_galaxy_packages_for_pulsar` tox environment and modify the
`test.sh` script so that when the `--for-pulsar` argument is passed:
- only the 4 packages used by Pulsar are tested
- mypy checks are skipped
- unit tests don't skip the tests marked with
`external_dependency_management` (i.e. those conda/container-related).
Also:
- Add missing pydantic requirement to the galaxy-objectstore package