$ go run main.go
$ curl -s \
-X POST \
-H "Content-Type: application/json" \
-d '{"item_code":"ITEM123", "price":100, "amount":2}' \
http://localhost:8080/generate_qr > output.png
$ curl -s \
-X POST \
-H "Authorization: Bearer [Your_JWT_Token_Here]" \
http://localhost:8080/verify_token |jq .
{
"message": "Successfully authenticated!"
}