You need to add the Odata.type and specify the contact entity manually I guess
"@odata.type": "Microsoft.Dynamics.CRM.Contact",
May be like this, but I have not tested it
"parameters": {
"entityName": "lists",
"actionName": "Microsoft.Dynamics.CRM.RemoveMemberList",
"recordId": "@outputs('Compose_Marketing_List_GUID')",
"@odata.type": "Microsoft.Dynamics.CRM.contact",
"item/ListMember/entitytype": "Microsoft.Dynamics.CRM.contact",
"item/ListMember/_entityid_value": "@items('Apply_to_each')?['_entityid_value']"
}