expires_unix is not giving consistent results

[glensc]

The problem

I was exploring cache contents and found something odd, r.expires_unix fluctuates 1s between different runs on same data.

    for r in session.cache.responses.values():
        print(f"{r.expires_unix}: {r.url}")

different outcome from different runs:

➜ grep 'https://api.trakt.tv/shows/134421/seasons?extended=episodes' /tmp/cache[456]
/tmp/cache4:1710720658: https://api.trakt.tv/shows/134421/seasons?extended=episodes
/tmp/cache5:1710720659: https://api.trakt.tv/shows/134421/seasons?extended=episodes
/tmp/cache6:1710720658: https://api.trakt.tv/shows/134421/seasons?extended=episodes

Expected behavior

It should be 1710720658 or 1710720659 on every run.

Environment

• requests-cache version: 1.2.0

[JWCook]

It looks like the current method for converting to a unix timestamp introduces a bit of randomness based on the delta from the current time and rounding the microseconds value to the nearest second. I can fix that.