Update d3 version in d3 example

examples/d3.html

@@ -6,7 +6,7 @@ docs: >
   The example loads TopoJSON geometries and uses d3 (<code>d3.geo.path</code>) to render these geometries to a SVG element.
 tags: "d3"
 resources:
-  - https://unpkg.com/d3@4.12.0/build/d3.js
+  - https://unpkg.com/d3@5.9.2/dist/d3.js
   - https://unpkg.com/topojson@3.0.2/dist/topojson.js
 ---
 <div id="map" class="map"></div>

examples/d3.js

@@ -85,7 +85,7 @@ const map = new Map({
 /**
  * Load the topojson data and create an ol/layer/Image for that data.
  */
-d3.json('data/topojson/us.json', function(error, us) {
+d3.json('data/topojson/us.json').then(function(us) {
 
   const layer = new CanvasLayer({
     features: topojson.feature(us, us.objects.counties)