Bump boto3 version for test-infra e2e tests

[vishalkatikineni]

Bump boto3 version to 1.38.15 for test-infra e2e tests. This is needed to add additional test for keyspaces-controller

[github-actions]

Hello @vishalkatikineni 👋 Thank you for opening an issue in ACK! A maintainer will triage this issue soon.

We encourage community contributions, so if you're interested in tackling this yourself or suggesting a solution, please check out our Contribution and Code of Conduct guidelines.

You can find more information about ACK on our website.