kubeadm: Update versions for 1.21

[RA489]

update current/minimal supported versions.
xref kubernetes/kubeadm#2362

[RA489]

/release-note-none

[RA489]

@kubernetes/sig-cluster-lifecycle-pr-reviews
/kind cleanup

[fabriziopandini]

/retest

[fabriziopandini]

/approve
/cc @neolit123

[neolit123]

the CI is failing here and kubeadm is receiving version 1.19 for some reason?

let's see it fails again:
/retest

[neolit123]

/priority backlog
/triage accepted

[neolit123]

@RA489

looks like some previous commits broke our unit tests a little, making them depend on hardcoded version strings.
you can apply this diff with git apply patch.diff and it should work.

diff --git a/cmd/kubeadm/app/cmd/alpha/kubeconfig_test.go b/cmd/kubeadm/app/cmd/alpha/kubeconfig_test.go
index 132ca498c90..b96f5147835 100644
--- a/cmd/kubeadm/app/cmd/alpha/kubeconfig_test.go
+++ b/cmd/kubeadm/app/cmd/alpha/kubeconfig_test.go
@@ -54,7 +54,7 @@ func generateTestKubeadmConfig(dir, id, certDir, clusterName string) (string, er
 		},
 		CertificatesDir:   certDir,
 		ClusterName:       clusterName,
-		KubernetesVersion: "v1.19.0",
+		KubernetesVersion: kubeadmconstants.MinimumControlPlaneVersion.String(),
 	}
 
 	var buf bytes.Buffer
diff --git a/cmd/kubeadm/app/cmd/certs_test.go b/cmd/kubeadm/app/cmd/certs_test.go
index 17979873950..a3451c269a2 100644
--- a/cmd/kubeadm/app/cmd/certs_test.go
+++ b/cmd/kubeadm/app/cmd/certs_test.go
@@ -330,7 +330,7 @@ func TestRunGenCSR(t *testing.T) {
 					ServiceSubnet: "192.0.2.0/24",
 				},
 				CertificatesDir:   certDir,
-				KubernetesVersion: "v1.19.0",
+				KubernetesVersion: kubeadmconstants.MinimumControlPlaneVersion.String(),
 			},
 		},
 	}
@@ -378,7 +378,7 @@ func TestGenCSRConfig(t *testing.T) {
 
 	// A minimal kubeadm config with just enough values to avoid triggering
 	// auto-detection of config values at runtime.
-	const kubeadmConfig = `
+	var kubeadmConfig = `
 apiVersion: kubeadm.k8s.io/v1beta2
 kind: InitConfiguration
 localAPIEndpoint:
@@ -389,8 +389,7 @@ nodeRegistration:
 apiVersion: kubeadm.k8s.io/v1beta2
 kind: ClusterConfiguration
 certificatesDir: /custom/config/certificates-dir
-kubernetesVersion: v1.19.0
-`
+kubernetesVersion: ` + kubeadmconstants.MinimumControlPlaneVersion.String()
 
 	tmpDir := testutil.SetupTempDir(t)
 	defer os.RemoveAll(tmpDir)

[RA489]

/test pull-kubernetes-bazel-test

[RA489]

@neolit123 Applied the patch diff PTAL.

[neolit123]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: fabriziopandini, neolit123, RA489

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• cmd/kubeadm/OWNERS [fabriziopandini,neolit123]

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