pfefferle/wordpress-webmention ensure unicode coverage in tests

[dougbeal]

Make sure unicode (as evidenced in https://github.com/snarfed/bridgy/issues/834) is covered in test.

(Originally published at: https://crw.moe/b/Zu)

[github-actions[bot]]

This issue is stale because it has been open 365 days with no activity. Remove stale label or comment or this will be closed in 5 days.