Adding mixpanel.com to self-service domains (#651)

Co-authored-by: Sorted Order Validation <[email protected]>

Author: aidenmitchell

self_service_creation_platform_domains.txt

@@ -34,6 +34,7 @@ issuu.com
 jensi.io
 larksuite.com
 lovable.app
+mixpanel.com
 mockflow.com
 netlify.app
 onrender.com