OTP verified with negative time delta

[Suraj Rana]

I was able to validate a TOTP with negative delta, lets say the OTP was generated on x timestamp then validating OTP on x-10 timestamp is working.

The issue is not reproducible at go playground, there the validation in failing, here's the go playground link : https://go.dev/play/p/xmCJkmRkzXA

This is the go version I'm using at my machine

➜  temp git:(main) ✗ go version  
go version go1.21.3 darwin/amd64

library version

github.com/pquerna/otp v1.4.0

here are the logs I get at my machine

➜  temp git:(main) ✗ go run main.go
2023/11/09 07:39:10 otp generated 118067
2023/11/09 07:39:10 2023-11-09 07:39:10.457564 +0530 IST m=+0.000233439
2023/11/09 07:39:10 2023-11-09 07:39:00.457564 +0530 IST m=-9.999766561
2023/11/09 07:39:10 otp verified

logs from go-playground

2009/11/10 23:00:00 otp generated 470478
2009/11/10 23:00:00 2009-11-10 23:00:00 +0000 UTC m=+0.000000001
2009/11/10 23:00:00 2009-11-10 22:59:59 +0000 UTC m=-0.999999999
2009/11/10 23:00:00 otp verification failed

Program exited.