New features

#1648 - This release adds update for ZeroSSL as a (free) alternative to Let's Encrypt, further broadening the range of service providers that win-acme can be used with. ZeroSSL account can be created using email signup, EAB credentials or an API key from an existing account. Requested by @trekmp.
#1684 - win-acme is now available as a .NET tool, so it can be installed or updated from the command line if you have .NET Core installed on your system using dotnet tool install win-acme --global. Note that it currently only works as a global tool and plugin support has not been tested yet. Idea from @jachin84.

Enhancements

Update various NuGet packages for upstream bugfixes
Update the Public Suffix List for uses that cannot download it dynamically each run
Add a random delay of 2 hours to the scheduled task to help alleviate potential performance issues for service providers. E.g. for new installs the scheduled task will run sometime beteen 9 am and 11 am. This does not affect existing installs and of course it is still configurable and customizable.
We now log if we're running as a 32 bit or a 64 bit build.
Add extra logging to track down possible bug #1678

#1680 - Fixed a bug that caused partially validated orders to fail in multithreaded mode, reported by @alexhass.
Fixed a bug that caused multithreaded mode to be enabled by default for people upgrading from 2.1.8 or below
#1675 - @Skulblaka fixed a bug in the DigitalOcean plugin that allows it to validate sub domains, reported by @wsaca. Thanks both!
#1676 - Version 2.1.11 would exit the process with code -1 (error) if one or more renewals were not due, thanks @RealAmes for noticing!