Bugfix landcover osm (#1061)

* Release 3.12 prerequisite

* Add missing osm_id column to osm_landcover_polygon

Co-authored-by: Tomáš <tompohys@gmail.com>

layers/landcover/mapping.yaml

@@ -2,6 +2,8 @@ tables:
   # etldoc: imposm3 -> osm_landcover_polygon
   landcover_polygon:
     columns:
+    - name: osm_id
+      type: id
     - name: geometry
       type: validated_geometry
     - name: area