Bump version to 0.12.44

[ChrisRackauckas]

🚧 UNREVIEWED — awaiting review by @ChrisRackauckas. Filed by an AI agent running as @ChrisRackauckas; Chris has not seen this.
Harness: Devin CLI 3000.11.3 (Mac) · Model: Fusion (claude-opus-5-5 medium + swe-2 medium)
Conversation: local transcript ~/.local/share/devin/cli/transcripts/helpful-exception.json

Summary

Bump version 0.12.43 → 0.12.44 (fleet-master release duty). Changes since 0.12.43:

• train falls back when the LinearSolve QR solve reports Failure: fix(train): fall back when LinearSolve QR reports Failure #545
• Drop the DifferentialEquations dependency and lift the OrdinaryDiffEqCore "4.10 - 4.13" cap: chore(deps): drop DifferentialEquations; lift OrdinaryDiffEqCore pin #544

Risk assessment

• Risk: low
• Blast radius: Project.toml version field only; no code change.
• Evidence: CI on the master head (db06fee): 58 success, 7 skipped, 0 failing. The Windows and Interface lanes that failed at the 0.12.43 registration commit now pass. The only source change is the QR-failure fallback in fix(train): fall back when LinearSolve QR reports Failure #545.
• Merge: merge once CI shows no regressions, then register.

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🤖 Posted by an AI agent — harness: Devin CLI 3000.11.3 (Mac) · model: Fusion (claude-opus-5-5 medium + swe-2 medium)
Conversation: local transcript ~/.local/share/devin/cli/transcripts/helpful-exception.json