Error in github_pr_destination: <organization_url> is not a valid GitHub url

Hi, when i want use CopyBara with pull request with below config

```
core.workflow(
name = "default",
origin = git.origin(
url = sourceUrl,
ref = "master",
),
destination = git.github_pr_destination(
url = destinationUrl,
destination_ref = "master",
pr_branch = "from_public_repo",
title = "pr from external public repo",
body = "this is a sample pull request",
integrates = [],
),
destination_files = glob(["external/**"]),
authoring = authoring.pass_thru("Copybara "),
transformations = [
core.move("", "external"),
],
```

I recived below info:

Could you please help?