[BETA] Get upload users signed url for a segment.

Retrieve a signed URL for uploading a segment user file.

This endpoint returns a pre-signed URL that allows you to securely upload a segment user file.

File requirements:

• The file must be in plain text format (“.txt”).
• It should not contain headers.
• Each line must represent a single opaque user ID.

The signed URL can be used to upload the file directly via an HTTP PUT request.

Returns

dict: A dictionary containing the signed URL and any additional metadata required for upload.