Fix package.json to bump Dashboard to v2.0.0-rc3. (#4861)

package-lock.json

 {
   "name": "kubernetes-dashboard",
-  "version": "2.0.0-rc2",
+  "version": "2.0.0-rc3",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {

package.json

 {
   "name": "kubernetes-dashboard",
-  "version": "2.0.0-rc2",
+  "version": "2.0.0-rc3",
   "repository": {
     "type": "git",
     "url": "https://github.com/kubernetes/dashboard.git"