Added timestamp GELF parameter

[MaKeG0]

Added timestamp (Seconds since UNIX epoch with optional decimal places for milliseconds), useful if the timestamp from the GELF needs to be different than the moment of upload (e.g. loading old logs)

[MaKeG0]

It's my second pull request, not sure i've done everything right.

[malinkinsa]

@MaKeG0
Thank you very much for your contribution.
Please take a look at the changes I've added. I believe they will improve the functionality.
The example will look as follows:

import asyncio
import asyncgelf

from datetime import datetime


async def main(message):
    handler = asyncgelf.GelfTcp(
        host='127.0.0.1',
    )
    event_time = "2024-02-06 08:25:56.789"
    timeformat = "%Y-%m-%d %H:%M:%S.%f"
    await handler.tcp_handler(message, datetime.strptime(event_time, timeformat).timestamp())

asyncio.run(main(message))

In this case, you can initialize the handler once for each event, passing your own timestamp without the need to reinitialize it.

If everything looks good, I'll add the information to the readme and merge your request into the master branch.

[MaKeG0]

No joking I was writing those edits in this moment, but without optionals, so mine was very messy (lots of if)

But there is something new that I wanted to add as I was doing the edits,that can be a new pull request.

The only thing I would add is the possibility to use lists of messages and/or timestamps in the TCP class.

I think would be possible to do the same with bulk updates with http, not sure if it's specific to graylog only

https://go2docs.graylog.org/5-0/getting_in_log_data/ingest_gelf.html

It just needs to handle the case of a list of both messages and timestamps (can be 1 message per timestamp or many messages per timestamp), join the list into a series of jsons separated by \n

I have a rough example. But I'll create a separate pr.

Thanks a lot!

[malinkinsa]

Then I'll merge it later tonight.