docs(samples): Remove Beam version from requirements.txt file

[VeronicaWasson]

Description

This sample pinned the Beam SDK version number. However, the latest template base image always uses the latest Beam, so it's not needed and can cause errors;

More information: b/374216225

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

[code-review-assist]

Hi VeronicaWasson,

Gemini is currently reviewing this pull request and will provide a full review shortly. In the meantime, here's a quick summary for you and other reviewers to get up to speed:

This pull request removes the pinned Beam SDK version from the requirements.txt file within the dataflow/flex-templates/getting_started directory. The intent, as stated in the description, is to resolve errors caused by pinning the Beam version when the latest template base image already uses the latest Beam version. The change involves a single line modification in dataflow/flex-templates/getting_started/requirements.txt, removing the specific version number and leaving only apache-beam[gcp]. This allows the build to use the latest available Beam SDK.

The change is straightforward and addresses a potential source of errors. The PR description also includes a reference to a related issue (b/374216225), which provides additional context.

---

Here's a little haiku to lighten the mood:

Version numbers gone,
Latest Beam now flows freely,
Errors fade away.

Thanks!
Gemini

[code-review-assist]

This pull request removes the pinned Beam SDK version from the requirements.txt file. This is a good change as it avoids potential conflicts with the base image's Beam version and aligns with the recommended practice of using the latest Beam SDK. The PR description clearly explains the rationale for the change and references the related bug report. The checklist is mostly complete, but there's one minor point to address regarding the README.