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GH-43536: [Python][CI] Add a Crossbow job with the free-threaded build (#43671)

### Rationale for this change

Testing with the free-threaded build is required for adding support for it. (see #43536)

### What changes are included in this PR?

- Add a Docker build with the CPython free-threaded build from deadsnakes.
- Add a Crossbow job to run said Docker build with Python 3.13t

### Are there any user-facing changes?

No.
* GitHub Issue: #43536

Lead-authored-by: Lysandros Nikolaou <lisandrosnik@gmail.com>
Co-authored-by: Antoine Pitrou <antoine@python.org>
Co-authored-by: Sutou Kouhei <kou@cozmixng.org>
Signed-off-by: Antoine Pitrou <antoine@python.org>