Add validation for resize config in get_transform

[Pritika2512]

Description

Adds validation for the resize configuration in get_transform() to ensure it is a list or tuple of length 2.

Changes

• Added input validation for resize parameter
• Raises clear error if invalid format is provided

Why this change?

Without validation, incorrect resize values could lead to runtime errors or unexpected behavior. This improves robustness and debugging.

Impact

• Improves reliability
• Prevents silent bugs
• No breaking changes

[ethanwhite]

Thanks for the contribution @Pritika2512 and apologies for taking a while to get to it. This looks good, but I have two small requested changes:

1. Remove the extra changes to the expand_bbox_to_square definition. Those changes are fine but they would belong in a separate PR.
2. Rebase the PR into a single commit.

Once those are done I think this is good to merge.