bump to 4.8.3

fleet.yaml

 defaultNamespace: ingress-nginx
 helm:
   releaseName: ingress-nginx
-  chart: https://github.com/kubernetes/ingress-nginx/releases/download/helm-chart-4.7.1/ingress-nginx-4.7.1.tgz
+  repo: https://kubernetes.github.io/ingress-nginx
+  chart: ingress-nginx
+  version: 4.8.3
   values:
     controller:
       ingressClassResource: