Doc upload token fix

[GregoryComer]

Summary

Unblock the doc upload job by using an explicit access token secret. I verified this works in #16989.

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/17078

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❌ 2 New Failures, 32 Pending, 1 Unrelated Failure

As of commit 82faa34 with merge base 4f3f329 ():

NEW FAILURES - The following jobs have failed:

• pull / test-lora-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 9205e0c49641fc950badc07dc9098a8233fbb6de54b6374b8767d21dfd29dd7a /exec failed with exit code 1
• pull / unittest-buck / linux / linux-job (gh)
  RuntimeError: Command docker exec -t a723b122b64afb663b9465b0747a001c6168318433ccc4cfd7c6ec7320b53696 /exec failed with exit code 3

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

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

• pull / unittest-buck / macos / macos-job (gh) (trunk failure)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 3

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