Update coremltools to 9b1

[metascroy]

This updates main to use coremltools 9.0b1.

We will pin the ExecuTorch GA release to use the official coremltools 9.0 release when it comes out.

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/13614

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❌ 1 New Failure, 1 Unrelated Failure

As of commit 440b14e with merge base 3db27cd ():

NEW FAILURE - The following job has failed:

• Build documentation / build (buck2) / Build doc (gh)
  At least one of the pre-conditions you specified did not hold

BROKEN TRUNK - The following job failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• trunk / test-huggingface-transformers-coreml (qwen3-1.7b|xnnpack|--quantize) / macos-job (gh) (trunk failure)
  RuntimeError: Command bash /Users/runner/work/_temp/exec_script failed with exit code 139

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