chore: bump pixi.lock to maturin 1.13.1 to fix py314t build

[sidd-27]

Summary

• Refreshes pixi.lock so the maturin>=1.9 constraint from fix: pin maturin>=1.9 to support Python 3.14t free-threaded builds #888 resolves to 1.13.1 across every pixi env (previously stuck at 1.10.2).
• Fixes the py3.14t-linux CI job, which still failed on fix: pin maturin>=1.9 to support Python 3.14t free-threaded builds #888-inclusive main with the same original error:

  💥 maturin failed
    Caused by: Unsupported Python interpreter for cross-compilation:
      .../py314t-venv/bin/python;
      supported interpreters are pypy, graalpy, and python (cpython)
  

Why 1.13.1 specifically

I grepped PyO3/maturin for the error string across release tags:

Version	Error present?
v1.10.1 → v1.12.5	yes
v1.13.0, v1.13.1	no

The offending branch was deleted in PyO3/maturin@98c4d728 (PR #3032, "refactor: unified interpreter resolution pipeline"). The new InterpreterResolver handles free-threaded CPython via an abiflags == \"t\" check and accepts a real venv executable path as Candidate::Executable, instead of falling into the pre-refactor cross-compile bail. conda-forge ships v1.13.1 today, so a plain pixi update maturin picks it up.

Context

• fix: pin maturin>=1.9 to support Python 3.14t free-threaded builds #888 tightened maturin = \"*\" → \">=1.9\" in pixi.toml / kornia-py/pyproject.toml but did not regenerate pixi.lock. Pixi pins to the lock, so the manifest bump was effectively inert for already-locked environments.
• Only pixi.lock changes here; no manifest edits.

Test plan

• pixi run -e py314t py-build succeeds (formerly failed in 50s at maturin develop).
• pixi run -e py314t py-test-threaded passes.
• All other py3.X-linux jobs still pass with the newer maturin (1.13.1 is backwards-compatible with 3.8–3.14).

🤖 Generated with Claude Code

[github-actions]

⚠️ PR Validation Warnings

❌ No linked issue found: This PR does not reference any issue. Please link to an issue using "Fixes #123" or "Closes #123" in the PR description.

---

Note: This PR can remain open, but please address these issues to ensure a smooth review process. For more information, see our Contributing Guide.