[VOL-1866] Changed module dependency to v12.0.0 of k8s client-go and v1.15.4 of k8s api/apimachinery in sync with other voltha components

Had to use pseudo-version corresponding to v12.0.0 of k8s client-go
because golang proxy is no longer serving the modules not complying
to Semantic Import Versioning rules including client-go v12.0.0.
Refer to https://github.com/kubernetes/client-go/issues/631 and
https://github.com/golang/go/issues/33558

Change-Id: I2e558bab7f0702f230761319eb5392a7d0532ea3
diff --git a/vendor/k8s.io/api/auditregistration/v1alpha1/generated.proto b/vendor/k8s.io/api/auditregistration/v1alpha1/generated.proto
index 70801a6..674debe 100644
--- a/vendor/k8s.io/api/auditregistration/v1alpha1/generated.proto
+++ b/vendor/k8s.io/api/auditregistration/v1alpha1/generated.proto
@@ -83,6 +83,12 @@
   // this service.
   // +optional
   optional string path = 3;
+
+  // If specified, the port on the service that hosting webhook.
+  // Default to 443 for backward compatibility.
+  // `port` should be a valid port number (1-65535, inclusive).
+  // +optional
+  optional int32 port = 4;
 }
 
 // Webhook holds the configuration of the webhook
@@ -132,8 +138,6 @@
   //
   // If the webhook is running within the cluster, then you should use `service`.
   //
-  // Port 443 will be used if it is open, otherwise it is an error.
-  //
   // +optional
   optional ServiceReference service = 2;