Arm backend: Bump Arm baremetal compilers to gcc 14.3

[zingo]

cc @digantdesai @freddan80 @per @oscarandersson8218

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/13317

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❌ 5 New Failures, 1 Unrelated Failure

As of commit 7b4c6f2 with merge base 17047ea ():

NEW FAILURES - The following jobs have failed:

• pull / android / run-emulator (gh)
  The process '/usr/bin/sh' failed with exit code 255
• trunk / test-arm-cortex-m-size-test (bare_metal) / linux-job (gh)
  RuntimeError: Command docker exec -t bc26feb357f283528221fe51f458ecaac27585e1b59ab4fc5357f0619ae68689 /exec failed with exit code 1
• trunk / test-models-arm-zephyr (add) / linux-job (gh)
  RuntimeError: Command docker exec -t 5ad903992fa995c7ebe15e7c2ed50fa9b9a41e1d6fadc7b6cdf26428a8aae191 /exec failed with exit code 1
• trunk / test-models-arm-zephyr (mv2) / linux-job (gh)
  RuntimeError: Command docker exec -t eead38698ca83cdd26e3cfd631080c3c4f125721767a4e00864ad5113e212e3b /exec failed with exit code 1
• trunk / test-models-arm-zephyr (softmax) / linux-job (gh)
  RuntimeError: Command docker exec -t c9384fd2540359b0932891af77f445929abf6d5c9cd0606b90b51d16855cc2b8 /exec failed with exit code 1

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

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

• Apple / build-demo-ios / macos-job (gh) (trunk failure)
  RuntimeError: Command bash /Users/runner/work/_temp/exec_script failed with exit code 65

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[digantdesai]

Nit: if the URL names are predictable, extract 14.3 out as a variable might be better to avoid missing some toolchain in future updates.