Update gateway api provider to v1alpha2

Co-authored-by: Tom Moulard <tom.moulard@traefik.io>

pkg/provider/kubernetes/gateway/fixtures/httproute/with_tls_configuration.yml

@@ -0,0 +1,24 @@
+---
+kind: GatewayClass
+apiVersion: gateway.networking.k8s.io/v1alpha2
+metadata:
+  name: my-gateway-class
+spec:
+  controllerName: traefik.io/gateway-controller
+
+---
+kind: Gateway
+apiVersion: gateway.networking.k8s.io/v1alpha2
+metadata:
+  name: my-gateway
+  namespace: default
+spec:
+  gatewayClassName: my-gateway-class
+  listeners: # Use GatewayClass defaults for listener definition.
+    - name: http
+      protocol: HTTP
+      port: 80
+      tls: { }
+      allowedRoutes:
+        namespaces:
+          from: Same