Fix spacing in ssh/certificate with goimports (#1178)

Author: dopey

command/ssh/certificate.go

@@ -184,10 +184,10 @@ $  step ssh certificate --kty OKP --curve Ed25519 mariano@work id_ed25519
 			sshPrivateKeyFlag,
 			sshProvisionerPasswordFlag,
 			sshSignFlag,
-                        flags.KTY,
+			flags.KTY,
 			flags.Curve,
 			flags.Size,
-                        flags.Comment,
+			flags.Comment,
 			flags.KMSUri,
 			flags.X5cCert,
 			flags.X5cKey,