Downgrade: raise OrdinaryDiffEqNonlinearSolve floor to 1.15 (#471)

The Downgrade (lts) lane fails at precompile with:

    MethodError: no method matching init(::NonlinearProblem,
        ::NonlinearSolveFirstOrder.GeneralizedFirstOrderAlgorithm;
        abstol, verbose)

OrdinaryDiffEqNonlinearSolve's compat floor of "1" lets the downgrade
resolver pick 1.14.1, which pulls NonlinearSolve 4.10.0. NonlinearSolve
4.10's loose compat (NonlinearSolveBase = "1.4.0 - 1",
NonlinearSolveFirstOrder = "1.2.0 - 1") permits the inconsistent pair
NonlinearSolveFirstOrder 1.7.0 + NonlinearSolveBase 1.14.0. The
init(::AbstractNonlinearProblem, ::AbstractNonlinearSolveAlgorithm)
method NonlinearSolveFirstOrder relies on only exists from
NonlinearSolveBase 1.15.0 onward (NonlinearSolveFirstOrder 1.8 bumped its
own floor to 1.15.0 for exactly this reason), so the pair fails to
precompile.

OrdinaryDiffEqNonlinearSolve 1.15 requires NonlinearSolve "4.12.0 - 4",
which requires NonlinearSolveBase "2", eliminating the broken option.
Verified on Julia 1.10 LTS by running the real julia-downgrade-compat@v2
action against the patched Project.toml: it resolves a consistent set
(OrdinaryDiffEqNonlinearSolve 1.15.0, NonlinearSolve 4.12.0,
NonlinearSolveBase 2.2.0, NonlinearSolveFirstOrder 1.11.1) and the full
test environment precompiles cleanly.

Co-authored-by: ChrisRackauckas-Claude <accounts@chrisrackauckas.com>

Author: ChrisRackauckas-Claude

Project.toml

@@ -28,7 +28,7 @@ ModelingToolkitBase = "1"
 OrdinaryDiffEq = "6, 7"
 OrdinaryDiffEqBDF = "1, 2"
 OrdinaryDiffEqDefault = "1, 2"
-OrdinaryDiffEqNonlinearSolve = "1, 2"
+OrdinaryDiffEqNonlinearSolve = "1.15, 2"
 OrdinaryDiffEqRosenbrock = "1, 2"
 OrdinaryDiffEqSDIRK = "1, 2"
 PreallocationTools = "0.4.27, 1"