[dotnet] Update target frameworks for .NET 6, .NET Framework 4.6.2, .NET Standard 2.0 and some improvments

[Romfos]

🤔 What's changed?

• .NET SDK was updated to .NET 7
• Target frameworks now: .NET 6, .NET Framework 4.6.2, .NET Standard 2.0
• Unit tests now will run for .NET 6 and .NET 7
• C# lang version was updated to 11
• Added minimal .editorconfig with some basic settings

⚡️ What's your motivation?

Why target frameworks were changed?

• Microsoft recommend to target .NET 6, .NET Standard and minimal supported .NET Framework
  https://learn.microsoft.com/en-us/dotnet/core/compatibility/core-libraries/6.0/older-framework-versions-dropped

• .NET Framework 4.6.1 is out of support, .NET Framework 4.6.2 is the older version that is still supported
  https://devblogs.microsoft.com/dotnet/net-framework-4-5-2-4-6-4-6-1-will-reach-end-of-support-on-april-26-2022/

Why lang version was updated?

• C# 10 and c C# 11 has some improvements for code generation around string interpolation plus a lot of new features
  https://devblogs.microsoft.com/dotnet/string-interpolation-in-c-10-and-net-6/
  https://devblogs.microsoft.com/dotnet/welcome-to-csharp-11/

Why target framework was changes for test project?

• .NET 5 is out of support, .NET 6 and .NET 7 are supported versions

🏷️ What kind of change is this?

• 🏦 Refactoring/debt/DX (improvement to code design, tooling, documentation etc. without changing behaviour)

♻️ Anything particular you want feedback on?

📋 Checklist:

• I agree to respect and uphold the Cucumber Community Code of Conduct
• I've changed the behaviour of the code
  • I have added/updated tests to cover my changes.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
• Users should know about my change
  • I have added an entry to the "Unreleased" section of the CHANGELOG, linking to this pull request.

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[Romfos]

Makefile was updated, please run ci one more time

[aslakhellesoy]

Hi @Romfos,

Thanks for your making your first contribution to Cucumber, and welcome to the Cucumber committers team! You can now push directly to this repo and all other repos under the cucumber organization! 🍾

In return for this generous offer we hope you will:

• ✅ Continue to use branches and pull requests. When someone on the core team approves a pull request (yours or someone else's), you're welcome to merge it yourself.
• 💚 Commit to setting a good example by following and upholding our code of conduct in your interactions with other collaborators and users.
• 💬 Join the community Slack channel to meet the rest of the team and make yourself at home.
• ℹ️ Don't feel obliged to help, just do what you can if you have the time and the energy.
• 🙋 Ask if you need anything. We're looking for feedback about how to make the project more welcoming, so please tell us!

On behalf of the Cucumber core team,
Aslak Hellesøy
Creator of Cucumber

[mpkorstanje]

Cheers. Looked good enough to me!