update docker-compose version (#1091)

update docker-compose version from 2.3 to 3

docker-compose.yml

@@ -1,5 +1,5 @@
 # This version must match the MAKE_DC_VERSION value below
-version: "2.3"
+version: "3"
 
 volumes:
   pgdata:
@@ -33,7 +33,7 @@ services:
     environment:
       # Must match the version of this file (first line)
       # download-osm will use it when generating a composer file
-      MAKE_DC_VERSION: "2.3"
+      MAKE_DC_VERSION: "3"
       # Allow DIFF_MODE, MIN_ZOOM, and MAX_ZOOM to be overwritten from shell
       DIFF_MODE: ${DIFF_MODE}
       MIN_ZOOM: ${MIN_ZOOM}