Update import statement in CreatePodcastShowModal component

[gabriel-glo]

Description of the Change

Update the import statement for PluginDocumentSettingPanel component to use unified extensibility API.

Closes #305

How to test the Change

No functional changes to the plugin.

Changelog Entry

Changed - Changed import of PluginDocumentSettingPanel component from @wordpress/edit-post to @wordpress/editor

Credits

Props @username, @username2, ...

Checklist:

• [x] I agree to follow this project's Code of Conduct.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my change.
• [ ] All new and existing tests pass.