1236: allow iframe communication in test (#1422)

relates to issue:
[1236](RaspberryPiFoundation/digital-editor-issues#1236)

Deploy is currently not configured to allow the scratch iframe to use
the postmessage api to communication with editor-ui.

Adding in the domain with the env variable should enable this on test.

Author: DNR500

.github/workflows/deploy.yml

@@ -60,7 +60,7 @@ on:
         type: string
       react_app_allowed_iframe_origins:
         required: false
-        default: "https://staging-editor.raspberrypi.org,https://staging-editor-static.raspberrypi.org"
+        default: "https://staging-editor.raspberrypi.org,https://staging-editor-static.raspberrypi.org,https://test-editor.raspberrypi.org"
         type: string
 
     secrets: