Ignore lint issues for deprecated Pool.Subjects()

- https://github.com/golang/go/blob/4aa1efed4853ea067d665a952eee77c52faac774/src/crypto/x509/cert_pool.go#L243-L244

cmd/pinniped/cmd/kubeconfig.go

@@ -720,6 +720,7 @@ func validateKubeconfig(ctx context.Context, flags getKubeconfigParams, kubeconf
 func countCACerts(pemData []byte) int {
 	pool := x509.NewCertPool()
 	pool.AppendCertsFromPEM(pemData)
+	//nolint:staticcheck // since we're not using .Subjects() to access the system pool
 	return len(pool.Subjects())
 }