Int cannot represent non-integer value

[jaydensmith]

.timestamp() returns POSIX timestamp as a float, so this causes an error because refresh_expires_in expects an int.

https://github.com/KundaPanda/strawberry-django-jwt/blob/54ad4b0a45f211b702b2f4c6541d4d8c5762050d/strawberry_django_jwt/utils.py#L255-L257