Enable concurrency #3
Description
Right now the bot is, as far as I understand, only performing a single operation at a time for all users and background jobs. That's okay in the sense that we don't really have any performance related complaints, but it's not ideal, especially with the ping command in use since this blocks while waiting for a response or timeout.
There is thread based concurrency available in the 13.x version of python-telegram-bot we use now. Before implementing that, it's worth considering updating to the asyncio based 20.x versions.