Unpin / widen test/ad Project.toml compat to resolve Mooncake ↔ SciMLSensitivity conflict

[ChrisRackauckas-Claude]

Summary

The test (AD, 1.11) job on #3502 fails at Pkg.instantiate with:

ERROR: LoadError: Unsatisfiable requirements detected for package SciMLSensitivity [1ed8b502]:
 SciMLSensitivity log:
 ├─possible versions are: 7.0.0 - 7.105.0 or uninstalled
 ├─restricted to versions 7.104.0 - 7 by project, leaving only versions: 7.104.0 - 7.105.0
 └─restricted by compatibility requirements with Mooncake [da2b9cff] to versions:
   [7.0.0 - 7.71.2, 7.95.0 - 7.103.0] or uninstalled — no versions left

Root cause

• SciMLSensitivity 7.104 and 7.105 both pin Mooncake = "0.5.25" in their Project.toml.
• In the test/ad env, the resolvable Mooncake is capped at 0.5.24 by DifferentiationInterface 0.7.16's WeakCompat entry (Mooncake = "0.5.1 - 0.5.24").
• test/ad/Project.toml had SciMLSensitivity = "7.104", which forced the resolver into the 7.104-7.105 range — but no Mooncake version in that range satisfies both SciMLSensitivity's 0.5.25+ floor and DI's 0.5.24 cap.

Change in this PR

Lower the SciMLSensitivity floor in test/ad/Project.toml from "7.104" to "7.89". SciMLSensitivity 7.89-7.103 have no direct Mooncake compat entry in the registry, so they would not re-apply that specific constraint. Mooncake = "0.4, 0.5" is left unchanged — already the widest range compatible with OrdinaryDiffEqCore v4's Mooncake = "0.4, 0.5" compat pin.

This is a test-env compat widening only; no source changes.

Honest caveat — this PR alone is not sufficient

Even after lowering the floor, the resolver is separately forced back into the 7.104-7.105 window by other deps in the env (SciMLBase 3 via OrdinaryDiffEqTsit5, FunctionWrappersWrappers 1 via OrdinaryDiffEqCore v4, FastBroadcast 1.3+, SciMLOperators 1.15+). So this one-line pin change does not on its own make Pkg.instantiate() succeed — verified locally.

The genuine unblock requires at least one of:

1. Mooncake 0.5.25 compat JuliaDiff/DifferentiationInterface.jl#988 — bump DI's Mooncake WeakCompat to include 0.5.25+, so SciMLSensitivity 7.105 and DI 0.7.16 can co-resolve.
2. A matching SciMLSensitivity Mooncake-compat relaxation so 7.105+ stops pinning Mooncake = "0.5.25" strictly (registry compat patch).
3. A targeted LinearSolve WeakCompat relaxation (today caps via "0.5.15 - 0.5" — not the immediate binding constraint but in the chain).

Opening this PR as the test/ad-side half of the fix: once any of the three above lands, this pin is already loosened and the resolver will succeed.

Test plan

• Confirmed the original failure locally (same Unsatisfiable log as CI).
• Confirmed that with this PR alone the resolver still fails (now blocked downstream of SciMLBase 3 / FunctionWrappersWrappers 1 forcing 7.104-7.105 regardless of the project floor). So the test/ad/Project.toml side is loosened correctly, but CI will only turn green once one of the three upstream fixes is in.
• Re-run test (AD, 1.11) after the upstream DI/SciMLSensitivity fix.

Co-Authored-By: Chris Rackauckas accounts@chrisrackauckas.com

[ChrisRackauckas-Claude]

Closing per request — SciMLSensitivity is out of scope for the v7 release unblock. The fix here was also incomplete (agent's own caveat: SciMLBase 3 / FastBroadcast 1.3 / SciMLOperators 1.15+ independently force 7.104-7.105, so the Mooncake conflict recurs regardless of the test/ad/Project.toml floor). Real fix lives upstream in JuliaDiff/DifferentiationInterface.jl#988 or a SciMLSensitivity registry compat patch.