Pagination code no longer seems to work.

The pagination code assumes a relative URL for the Next/Previous links

```
// GetPage will fetch a page via the Link object and decode it from out.
// Should be used like `client.GetPage(link.Previous, make([]Organization, 0))`
func (c *Client) GetPage(p Page, out interface{}) (*Link, error) {
return c.rawWithPagination("GET", strings.TrimPrefix(p.URL, c.Endpoint), out, nil)
}
```
It prepends the Endpoint URL to the link URL. This worked until recently as Sentry .io API now returns full URLs for the link.

Start at the GetPage function shown in the issue and trace how it calls rawWithPagination and handles p.URL. Verify the behavior with both relative and full Next/Previous links; the work is done when full Sentry API URLs are fetched correctly without an incorrect Endpoint prefix.

Written by the indexing model from the issue text.