Timestamp is not monotonic

[lzap]

There is a chance that the time is generated in non-monotonic sequence, AWS does refuse to accept such batch with the following error:

zerolog: could not write event: operation error CloudWatch Logs: PutLogEvents, https response error StatusCode: 400, RequestID: 04f4acf4-d527-47c1-be20-5df5fbf8bf61, InvalidParameterException: Log events in a single PutLogEvents request must be in chronological order.

In fact, we do see this bug in our stage system from time to time. I fixed it in my fork:

lzap/cloudwatchwriter2@a109d00

Leaving an issue here just in case.