Replace time.sleep() with asyncio.sleep()

[CashWilliams]

Attempt to fix #172, #178, and #191.

Losely based on #173, but using asyncio.sleep instead of task.sleep.

It should be noted I have no idea what I'm doing 😃

[ollo69]

You cannot make async a function that perform sync activities just because you want to call 1 async method. You are mixing sync and async, this is totally wrong and would be worst that original implementation.

[koen241]

Indeed did not fix the problem.