added additiona var for aurora

Description

Added additional Variables ( retention_period and backup_window) for aurora cluster

Please ensure that the following steps are completed before submitting the pull request:

[X] Code follows the Terraform best practices and style guidelines.
[X] Changes are appropriately documented, including any necessary updates to README or other documentation files.
[X] Unit tests have been added or updated to cover the changes introduced by this pull request.
[X] Changes have been tested locally and verified to work as expected.
[X] The code has been reviewed to ensure it aligns with the project's goals and standards.
[X] Dependencies and backward compatibility have been considered and addressed if applicable.

Please delete options that are not relevant.

[ ] Bug fix (non-breaking change which fixes an issue)
[X] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
[ ] Intermediate change (work in progress)

Added additional Variables ( retention_period and backup_window) for aurora cluster