Remove expressway from ramps (#1602)

#1313 added `expressway` tagging to the transportation layer. However, this also added the `expressway` attributes to ramps where it doesn't make sense (ramps by definition are controlled-access roads in all cases).  This PR corrects this by dropping the `expressway` attribute from ramps where it doesn't make sense to do so.

See also ZeLonewolf/openstreetmap-americana#1017

layers/transportation/transportation.sql

@@ -62,7 +62,7 @@ SELECT osm_id,
        NULLIF(service, '') AS service,
        access,
        CASE WHEN toll = TRUE THEN 1 END AS toll,
-       CASE WHEN highway NOT IN ('', 'motorway') AND expressway = TRUE THEN 1 END AS expressway,
+       CASE WHEN highway NOT IN ('', 'motorway') AND NOT is_ramp AND expressway = TRUE THEN 1 END AS expressway,
        NULLIF(layer, 0) AS layer,
        "level",
        CASE WHEN indoor = TRUE THEN 1 END AS indoor,