Invalid QR Code when secret_key is already existing

[GeorgeMonroyo]

When we provide a secret_key, example coming from a database and generate the OTP, using the code below, the URL generated is encoded version of the secret key and thus validate will fail because the secret key stored in the authenticator is encoded value of the secret key

key, err := totp.Generate(totp.GenerateOpts{
Issuer: "Issuer",
AccountName: username,
Secret: []byte(user.SecretKey),
})

var buf bytes.Buffer
img, err := key.Image(200, 200)
if err != nil {
panic(err)
}
png.Encode(&buf, img)