[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/klog/OWNERS b/vendor/k8s.io/klog/OWNERS
index d0168e8..380e514 100644
--- a/vendor/k8s.io/klog/OWNERS
+++ b/vendor/k8s.io/klog/OWNERS
@@ -1,5 +1,13 @@
 # See the OWNERS docs at https://go.k8s.io/owners
-
+reviewers:
+  - jayunit100
+  - hoegaarden
+  - andyxning
+  - neolit123
+  - pohly
+  - yagonobre
+  - vincepri
+  - detiber
 approvers:
   - dims
   - thockin