Move from `netstandard2.0` to modern targets, `net8` or `net9`

[dkropachev]

Beside that netstandard2.0 has 6 HIGH and 1 MEDIUM security issues in System.Net.Http.
It has async API limitations that does not allow us to have better API, read: #126

It was decided not to do that to enable users who stuck on old runtimes.
Let's go back to this issue in late 2026 or 2027, after csharp-rs-driver is released, we will asses it's adoption and can properly decide which road we take.

Updates blocked by old targets:

• Microsoft.NET.Test.Sdk

[wprzytula]

As of now we are not ready to do that.

Can you explain why? Then people reading this issue will be able to track whether we are ready for the change.

[dkropachev]

As of now we are not ready to do that.

Can you explain why? Then people reading this issue will be able to track whether we are ready for the change.

I have change the language, please take a look