Restore support for .NET 8

[flcdrg]

Describe the bug

Since #908 the Verify.EntityFramework package is no longer compatible with .NET 8 (whereas Verify.EntityFrameworkClassic still is):

Package Verify.EntityFramework 14.0.0 is not compatible with net8.0 (.NETCoreApp,Version=v8.0). Package Verify.EntityFramework 14.0.0 supports: net10.0 (.NETCoreApp,Version=v10.0)

.NET 8 is a LTS release and still supported until November 10, 2026. It would be nice stay usable with .NET 8 until at least then.

Minimal Repro

1. Create a .NET 8 project
2. Attempt to add a package reference to Verify.EntityFramework

[flcdrg]

Hmm.. maybe this becomes messy:

error NU1202: Package Microsoft.EntityFrameworkCore.Relational 10.0.0 is not compatible with net8.0 (.NETCoreApp,Version=v8.0). Package Microsoft.EntityFrameworkCore.Relational 10.0.0 supports: net10.0 (.NETCoreApp,Version=v10.0)

Sticking with 13.1.2 might be the easier option

[flcdrg]

12.4.0 is the last version to support EF Core 8.

[SimonCropp]

yeah when i gave this a cursory look a while back. the new EF had breaking changes that made it not possible to support both versions from one nuget.

sorry