Add requires.tables to <layer>.yaml (#1236)

**NOTE** this can only be merged after the next tools version is released.

Added required Postgres tables to the `<layer>.yaml` definition.
Close: #1220

PR of tools: https://github.com/openmaptiles/openmaptiles-tools/pull/370

layers/transportation_name/transportation_name.yaml

@@ -1,7 +1,9 @@
 layer:
   id: "transportation_name"
   # transportation_name relies on the function highway_class() defined in transportation layer
-  requires: "transportation"
+  requires:
+    layers:
+      - transportation
   description: |
       This is the layer for labelling the highways. Only highways that are named `name=*` and are long enough
       to place text upon appear. The OSM roads are stitched together if they contain the same name