Update poll.js to include XML Header in fetch request

[riathakkar]

Description

Fixes b/362304568

Note: Before submitting a pull request, please open an issue for discussion if you are not associated with Google.

Checklist

• I have followed Sample Guidelines from AUTHORING_GUIDE.MD
• README is updated to include all relevant information
• Tests pass: nox -s py-3.9 (see Test Environment Setup)
• Lint pass: nox -s lint (see Test Environment Setup)
• These samples need a new API enabled in testing projects to pass (let us know which ones)
• These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• Please merge this PR for me once it is approved

[riathakkar]

How do we close this PR? @jinglundong

[jinglundong]

I approved the PR. Let's wait for the Kokoro CI results.

[jinglundong]

I just clicked re-run all checks to see if those Kokoro CI can be completed.

[jinglundong]

I don't know why the Kokoro CIs are not triggered. We may need approval from iennae, the other reviewer, as well.

[jinglundong]

3 tests/checks failed. Could you please take a look and ideally fix them? Thanks!

[riathakkar]

@jinglundong I cant view the build results it says permisson denied. Im wondering if the linter is failing because its a js file with the python linter?

[riathakkar]

@jinglundong I rerean the linter and it passes for some python.

nox > * py-2.7: failed
nox > * py-3.8: success
nox > * py-3.9: failed
nox > * py-3.10: failed
nox > * py-3.11: failed
nox > * py-3.12: success

What i dont understand is if the js file is ever going to pass a python linter? I dont know why this file is in this repository.

[jinglundong]

@kennethye1 At first glance, I was wondering if these integration tests failed due to the lifecycle policy enforcement. However, python-3.8 succeeded but python-3.11 failed. Are they really testing the modernized path?

Edit: seems like we are testing the modernized path. https://github.com/search?q=repo%3AGoogleCloudPlatform%2Fpython-docs-samples+ubuntu22&type=code, but we aren't really testing specific python minor versions from what I'm reading.

[jinglundong]

@SandeepTuniki Could you help triage this PR?

[SandeepTuniki]

@SandeepTuniki Could you help triage this PR?

harisam@ is looking into this PR.

[chalmerlowe]

Took a quick look at the build logs to see why these CI/CD checks are not passing.
Will discuss internally on b/362304568

[SandeepTuniki]

@riathakkar Perhaps we can close this PR now, since you raised another PR in #13022 and got it merged?