Use test branch of pelias/schema

has disable_fielddata and improved synonyms
(https://github.com/pelias/schema/pull/310)

projects/north-america/docker-compose.yml

@@ -9,7 +9,7 @@ services:
     restart: always
     ports: [ "4400:4400" ]
   schema:
-    image: pelias/schema:master
+    image: pelias/schema:na-synonyms
     container_name: pelias_schema
     volumes:
       - "./pelias.json:/code/pelias.json"