Is your feature request related to a problem? Please describe.

Issue #1843 raised the concern of accessing remote resources during testing. While this isn't a serious limitation for us in CI, it might be a problem for other package vendors (i.e. debian), which block network access during package builds and test runs.

This is a problem for librosa's tests, which either depend on remotely hosted (or git submoduled) resources (librosa-test-data repo) or hosted example data.

Describe the solution you'd like
We can add a pytest skip flag to any tests that require access to either the test data submodule. This way, a user can set an environment flag (or perhaps some other mechanism) to disable executing tests we know will be problematic. This would have no impact on our CI setup.