XADD uses seconds since epoch instead of milliseconds since epoch

[alexporter8013]

Describe the bug
A clear and concise description of what the bug is.
Add the code you are trying to run, the stacktrace you are getting and anything else that might help.

To Reproduce
Steps to reproduce the behavior:

1. Use xadd and inspect return value.

Expected behavior
From https://redis.io/commands/xadd/:

Both quantities are 64-bit numbers. When an ID is auto-generated, the first part is the Unix time in milliseconds of the Redis instance generating the ID. The second part is just a sequence number and is used in order to distinguish IDs generated in the same millisecond.

Source Code

Link: https://github.com/cunla/fakeredis-py/blob/053ae9e5805527f6d6dc4c1acc269226c0c7ca58/fakeredis/_stream.py#LL51C13-L51C46

Repeated for clarity:
ts, seq = int(time.time() + 1), 0