Updating Bitcoin.Net target to new dotnet versions

[Coding-Enthusiast]

We plan on updating Bitcoin.Net target framework to a new .net version.

Currently Bitcoin.Net targets .Net Standard 2.1, although it is not technically obsolete but it is no longer updated and it is missing a lot, including APIs and the new language features.
You already can't use Bitcoin.Net in any projects targeting any .net framework versions and the old .net core/.net releases have already reached their end of support (5 and older).

The best choice seems to be .Net 8 (to be released on Nov. 2023) since it is the next LTS.
Certain APIs such as the new 128-bit integers were introduced in version 7+, we are going to need these at some point for our cryptography implementation. But .Net 7 is STS and its end of support is close (May 2024).

Bitcoin.Net will continue to target a single framework because we don't see the point in targeting more frameworks based on what was explained above.