Feature fixed on v2.4:
* correctly retrieve account information when it was already registred (afb7e988)
* when DNS Host configuration is an IP address, use it correctly as name server (2776348a)
* improve code stability by following hints from [pyright](https://github.com/microsoft/pyright)
(raises more explicit errors, fix function return type...)
Continuous Integration:
* Remove tests for Debian Jessie and add tests for Debian Bullseye (a745e655)
* Validate all tests with the [pebble](https://github.com/letsencrypt/pebble) tiny ACME server
Documentation:
* Move documentation from wiki to [`/documentations`](./documentations) directory so we can always synchronize it with code