Bitccl

We now support Python 3.8+ only

Properly use event loop
We now support using `asyncio.run` without crashes

Python 3.10 support

Better, safer compiler by using RestrictedPython

Now it should not be possible to get access to arbitrary modules via existing python objects available.

For more details see [How does BitCCL secure the users](https://github.com/bitcartcc/bitccl/blob/master/README.md#how-does-bitccl-secure-the-users)

Drop python 3.6 support (we support 3 latest python releases)

License change to LGPLv3+

Python 3.9 support