Update to .NET 5 with EF Core 5

[bart-degreed]

The plan is to update the codebase to depend on .NET 5 with EF Core 5. This means the 3.x framework versions will no longer work with this version of JADNC. We're doing this to enable future enhancements in the next major release, such as #1029, #935 and #664.

[bart-degreed]

Part of this work includes updating the version table.