fix: add support for multiple ingress classes

pkg/provider/kubernetes/ingress/fixtures/v18-Ingress-with-multiple-ingressClasses_ingress.yml

@@ -0,0 +1,30 @@
+kind: Ingress
+apiVersion: networking.k8s.io/v1beta1
+metadata:
+  name: ""
+  namespace: testing
+spec:
+  ingressClassName: traefik-lb
+  rules:
+  - http:
+      paths:
+      - path: /bar
+        backend:
+          serviceName: service1
+          servicePort: 80
+
+---
+kind: Ingress
+apiVersion: networking.k8s.io/v1beta1
+metadata:
+  name: ""
+  namespace: testing
+spec:
+  ingressClassName: traefik-lb2
+  rules:
+    - http:
+        paths:
+          - path: /foo
+            backend:
+              serviceName: service1
+              servicePort: 80