Clean up debug messages on boot

[mattrasband]

On boot, the client session prints some errors because we create the client outside a coroutine:

Creating a client session outside of coroutine
client_session: <aiohttp.client.ClientSession object at 0x100e76860>

These should be cleaned up to not spam users with unnecessary info.

[alexpnt]

Actually, this is not the recommended way of creating ClientSession . That's why this warning is appearing.

I submitted a fix here: #12