Downgrade CI resolves incompatible OrdinaryDiffEqRosenbrock/Core versions

Problem

The Core Downgrade workflow currently fails on master and on unrelated pull requests because it resolves an incompatible pair:

• OrdinaryDiffEqRosenbrock v1.8.0
• OrdinaryDiffEqCore v1.32.0

OrdinaryDiffEqRosenbrock then fails to precompile:

WARNING: could not import OrdinaryDiffEqCore.namify into OrdinaryDiffEqRosenbrock
ERROR: LoadError: UndefVarError: `namify` not defined

The failure surfaces when Core/domain_tests.jl loads OrdinaryDiffEqRosenbrock; it is not a DiffEqCallbacks test assertion.

CI evidence

• Current master failure at e1a166bf: https://github.com/SciML/DiffEqCallbacks.jl/actions/runs/30976864565
• Unrelated documentation PR failure with the same versions and stack trace: https://github.com/SciML/DiffEqCallbacks.jl/actions/runs/31045683568
• Last successful Downgrade run at c8a16d2e: https://github.com/SciML/DiffEqCallbacks.jl/actions/runs/30533208229

Bisect result

The first failing repository run was at 1fac1f5d. The only commit between the last success and first failure is 1fac1f5d (QA: scan the Functors package extension (#331)), which changed only test/qa/Project.toml and test/qa/qa.jl. Project.toml and the Downgrade workflow are identical at the last-success and first-failure commits, including:

OrdinaryDiffEqRosenbrock = "1.8.0, 2"

Therefore there is no repository source commit to bisect further; the transition is resolver/registry-state dependent.

Local reproduction

On Julia 1.10.11 in a fresh local environment:

using Pkg
Pkg.add([
    PackageSpec(name = "OrdinaryDiffEqCore", version = v"1.32.0"),
    PackageSpec(name = "OrdinaryDiffEqRosenbrock", version = v"1.8.0"),
])
using OrdinaryDiffEqRosenbrock

This exits 1 with the same missing namify import.

Updating only OrdinaryDiffEqRosenbrock to v1.18.1 while retaining OrdinaryDiffEqCore v1.32.0 loads successfully:

loaded OrdinaryDiffEqRosenbrock 1.18.1
loaded OrdinaryDiffEqCore 1.32.0

Suggested fix

Raise the test compat floor to a known compatible Rosenbrock release, for example OrdinaryDiffEqRosenbrock = "1.18.1, 2", or add the appropriate upstream compatibility bound so the downgrade resolver cannot select the incompatible pair.

Start with test/qa/Project.toml and the Core/domain_tests.jl entry point, then inspect the Downgrade workflow and reproduce the resolver failure on Julia 1.10.11. Done means the downgrade environment no longer selects the incompatible OrdinaryDiffEqRosenbrock/Core pair and the affected workflow passes.