It seems that the latest version bump breaks the unit test of acoustic_substepping. Below is part of the error messages:
Error in testset Acoustic divergence damping [Float64]:
Error During Test at /home/runner/work/Breeze.jl/Breeze.jl/test/acoustic_substepping.jl:311
Got exception outside of a @test
UndefVarError: `maybe_initialize_state!` not defined in `Breeze.TimeSteppers`
Suggestion: check for spelling errors or missing imports.