Add temporary fix for traffic flow cors problem

src/utils/api-client.js

@@ -28,8 +28,9 @@ export function get_lam_points(api_url, set_state) {
 }
 
 export function get_free_flow_speeds(api_url, set_state) {
-  return fetch(`${api_url}/api/v1/data/free-flow-speeds`)
-    .then((res) => res.json())
+  return fetch("/free-flow-speeds.json")
+    .then((res) => res.text())
+    .then((t) => JSON.parse(t))
     .then((json) => {
       const tms_data = json.tmsFreeFlowSpeeds;
       set_state((prevState) => {