Bump goversion to v1.21 align with kubernetes

Signed-off-by: kerthcet <[email protected]>

go.mod

@@ -1,6 +1,6 @@
 module sigs.k8s.io/leader-worker-set
 
-go 1.20
+go 1.21
 
 require (
 	github.com/google/go-cmp v0.6.0
@@ -57,6 +57,7 @@ require (
 	go.uber.org/multierr v1.11.0 // indirect
 	go.uber.org/zap v1.26.0 // indirect
 	golang.org/x/exp v0.0.0-20220722155223-a9213eeb770e // indirect
+	golang.org/x/mod v0.14.0 // indirect
 	golang.org/x/net v0.19.0 // indirect
 	golang.org/x/oauth2 v0.12.0 // indirect
 	golang.org/x/sys v0.16.0 // indirect
@@ -71,9 +72,8 @@ require (
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 	k8s.io/component-base v0.29.1 // indirect
+	k8s.io/gengo v0.0.0-20230829151522-9cce18d56c01 // indirect
 	k8s.io/kube-openapi v0.0.0-20231010175941-2dd684a91f00 // indirect
 	sigs.k8s.io/json v0.0.0-20221116044647-bc3834ca7abd // indirect
 	sigs.k8s.io/yaml v1.4.0 // indirect
-	k8s.io/gengo v0.0.0-20230829151522-9cce18d56c01 // indirect
-	golang.org/x/mod v0.14.0 // indirect
 )