Don't use problem mutation in tests

Required to be compatible with the next DiffEqBase release

Initialization can modify state

v2.12.0

save_end

Bug fixes

v2.11.1

fix scoping error

Stiff SDEs

v2.11.0

force stepfail once before erroring

No muladd macro DiffEqBase, use MuladdMacro.jl

v2.10.0

No muladd diffeqbase

Callback fixes

v2.9.1

fix callback saving

Interface enhancements

v2.9.0

fix isnan setup

remove special problem usage in tests

v2.8.0

update minimum version

seeding and saving fixes

v2.7.1

reseed even custom noise process

stochastic seeding

v2.7.0

Update REQUIRE