feat: .NET 9 support

[skolmer]

Description

This PR adds support for .NET 9.

Npgsql.EntityFrameworkCore.PostgreSQL is not released yet so I had to reference 9.0.0-rc.2 in the tests.

[what-the-diff]

PR Summary

• Software Update: Updated the software version used (.NET) from the older version (8.0.x) to the latest, more resilient and robust version (9.0.x). This change has been implemented in three crucial workflow files, making the system better and error-free.
• Platform Refinement: Enhanced several project frameworks to incorporate .NET 9.0, resulting in the improved functioning of multiple key software components such as ElasticSearch, Entity Framework, and Gridify tests. This ensures our program capabilities are better and up-to-date.
• Package Updates: We've updated multiple software libraries, or packages (including Entity Framework Core), from the previous version to the new one. This helps to remove any bugs and adds new features that come with the latest versions. Also, some other libraries used in test projects were updated for a better system performance.
• New Package Inclusion: New libraries supporting .NET 9.0 was added to enhance the Entity Framework and Gridify software components. This way, we ensure that these components can optimally utilize the benefits and features of the updated version (.NET 9.0).

[alirezanet]

Awesome thanks 👌

[k94ll13nn3]

Hello @alirezanet, do you have an ETA on when the package will be available on NuGet?

[alirezanet]

Hi @k94ll13nn3,
I just released v2.15.1 with dotnet 9 support