refactor(requests): improve retry policy configuration

[clemlesne]

Since multiple Azure CLI extensions are still using this project as a backend for managing API requests, I'm sending this PR.

This includes:

• Increase the total number of retries to 6
• Enable retries for 429 Too Many Requests

Impact:

When using the Azure CLI with the Azure DevOps commands, commands often fail into error due to rate limiting. Retriable and non-retriable errors are not distinguishable from each others, it complexities a lot the developer's ability to automate.

Relates: https://github.com/Azure/azure-cli/issues/24886#issuecomment-1874344677

[lmazuel]

Hi, this package is deprecated and no longer receives update. Please sync with the CLI team on their plan to stop using this package. Thanks,