Update T Token Dashboard version to v1.6.0-pre

`v1.5.0` is live!

Author: r-czajkowski

package.json

@@ -1,6 +1,6 @@
 {
   "name": "token-dashboard",
-  "version": "1.5.0-pre",
+  "version": "1.6.0-pre",
   "private": true,
   "dependencies": {
     "@0x/subproviders": "^6.6.1",