upper version constraints against ef core 3

[danielgerlag]

• EF Core 3.0 introduces breaking changes
• EF Core 3.0 targets .net standard 2.1 which will not be supported by .Net Framework
• This PR places an upper limit on the EF core version of the host application, as this incompatibility was creating confusion that workflow core is not compatible with .net core 3.0, which is false

[terry-delph]

HI @danielgerlag

I think the MySQL persistence provider may also need this same constraint.

It depends on Pomelo.EntityFrameworkCore.MySql.

If we were to upgrade to Pomelo.EntityFrameworkCore.MySql 3.0.0-rc3.final

Dependency chain of Pomelo is:

• Microsoft.EntityFrameworkCore.Relational >= 3.0.0: Microsoft.EntityFrameworkCore.Relational/

  • Microsoft.EntityFrameworkCore >= 3.0.0