Bump client-go to v0.18.9

This PR bumps the client-go version to v0.18.9
as its a blocker for linkerd/linkerd2#4191

Signed-off-by: Tarun Pothulapati <[email protected]>

Author: Pothulapati

go.mod

@@ -4,21 +4,16 @@ go 1.12
 
 require (
 	github.com/fatih/color v0.0.0-20180516100307-2d684516a886
-	github.com/ghodss/yaml v1.0.0 // indirect
-	github.com/gogo/protobuf v1.3.0 // indirect
-	github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b
-	github.com/google/gofuzz v1.0.0
 	github.com/googleapis/gnostic v0.3.1 // indirect
-	github.com/gregjones/httpcache v0.0.0-20190611155906-901d90724c79 // indirect
 	github.com/imdario/mergo v0.3.7 // indirect
-	github.com/inconshreveable/mousetrap v1.0.0
+	github.com/inconshreveable/mousetrap v1.0.0 // indirect
+	github.com/jessevdk/go-flags v1.4.0 // indirect
 	github.com/mattn/go-colorable v0.1.2 // indirect
 	github.com/mattn/go-isatty v0.0.9 // indirect
 	github.com/mitchellh/go-homedir v0.0.0-20161203194507-b8bc1bf76747
-	github.com/pkg/errors v0.0.0-20180311214515-816c9085562c
+	github.com/pkg/errors v0.8.1
 	github.com/spf13/cobra v0.0.0-20180629152535-a114f312e075
-	github.com/spf13/pflag v1.0.5
-	k8s.io/api v0.17.4
-	k8s.io/apimachinery v0.17.4
-	k8s.io/client-go v0.17.4
+	k8s.io/api v0.18.9
+	k8s.io/apimachinery v0.18.9
+	k8s.io/client-go v0.18.9
 )