fix: pins financial-advisor-spanner itables version

[tombotch]

Description

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Fixes itables not loading properly by pinning the version.

[code-review-assist]

Hi @tombotch and reviewers,

I'm currently reviewing this pull request and will post my full review in a few minutes. In the meantime, here's a quick summary to get everyone up to speed:

This PR addresses an issue with the itables library in the finance-advisor-spanner sample application. The problem was that itables wasn't loading correctly. The solution implemented in this PR is to pin the itables version to 2.1.5 in the requirements.txt file. This change ensures that the application uses a compatible version of itables, resolving the loading issue.

Specifically, the only change is a modification to the gemini/sample-apps/finance-advisor-spanner/requirements.txt file. Line 3 was changed from itables to itables == 2.1.5 to specify the exact version.

Debugging's a quest,
Pinning versions, a test,
Code now runs with zest!

[code-review-assist]

This pull request pins the itables library to version 2.1.5, which is a good practice for reproducibility and avoiding unexpected issues from library updates. However, the provided reasoning for the change "Fixes itables not loading properly" is vague. Providing more context on the specific issue encountered would make the PR description more informative. Additionally, more details on the impact of this change and any potential side effects would be beneficial. Here are a few suggestions to further improve this change.

[code-review-assist]

Consider specifying the version for all other dependencies as well for better reproducibility. This will help ensure that the application behaves consistently across different environments and over time. You can use pip freeze > requirements.txt to generate a list of all dependencies and their versions after setting up your virtual environment.

Suggested change

	itables == 2.1.5
	itables==2.1.5