Upgraded to .Net 7

[SefaOray]

This PR upgrades all project within the solution to .Net 7. This is created to address the issue:

#475

[oscarjaergren]

Would love to get a new release with this

[cedwards-telis]

This PR still has old references that cause issues with ef 7.0. Obviously you can use ef core 6.0 with .net 7.0 but you might want to run ef 7.0.

https://github.com/SefaOray/Mapster/blob/development/src/Mapster.EFCore/packages.config

Line 3 should be

<package id="EntityFramework" version="7.0.0" />

And

https://github.com/SefaOray/Mapster/blob/development/src/Mapster.EFCore/Mapster.EFCore.csproj

Line 15 should be

<PackageReference Include="Microsoft.EntityFrameworkCore" Version="7.0.0" />

If you don't do this and run with ef 7.0 you'll get runtime exceptions like

System.MissingMethodException: 'Method not found: 'System.Type Microsoft.EntityFrameworkCore.Metadata.ITypeBase.get_ClrType()'.' due to conflicting versions.

I suppose that there is a way to handle complex mixed version packages but I don't know it....

[HenricFranssonXM]

Do you have a release plan for official .Net 7 support?

[cedwards-telis]

Actually I think the issue I am having with

System.MissingMethodException: 'Method not found: 'System.Type Microsoft.EntityFrameworkCore.Metadata.ITypeBase.get_ClrType()'.' due to conflicting versions.

may be because the verison of the ef core plugin on Nuget was not complied on the right version of ef core - dotnet/efcore#26701 (comment)

[andrerav]

Fixed by #496. Thank you @SefaOray!