Update go.mod and go.sum to latest version from networkservicemesh/cm…

…d-nsmgr@main

PR link: networkservicemesh/cmd-nsmgr#432

Commit: af3f81a
Author: Авраменко Михаил
Date: 2021-12-16 17:58:44 +0700
Message:
  - manual update (#432)
Signed-off-by: NSMBot <nsmbot@networkservicmesh.io>

apps/nsmgr/nsmgr.yaml

@@ -17,7 +17,7 @@ spec:
     spec:
       serviceAccount: nsmgr-sa
       containers:
-        - image: ghcr.io/networkservicemesh/ci/cmd-nsmgr:5dcafa6
+        - image: ghcr.io/networkservicemesh/ci/cmd-nsmgr:af3f81a
           imagePullPolicy: IfNotPresent
           name: nsmgr
           ports: