chore: upgrade F# lang to 8.0 and Microsoft.Build.Tasks.Core to 18.3.3 - #461

There are two things got broken at same time:

• 560fea8 FS3880: Language version '6.0' is out of support
• b7a8171 MissingMethodException: Method not found: Void Microsoft.Build.Framework.IMetadataContainer.RemoveMetadataRange(System.Collections.Generic.IEnumerable1<System.Stri ng>). NUKE loads Microsoft.Build.Tasks.Core version 18.0.2, while the installed .NET SDK requires now a newer version.

IMPORTANT

• If the PR touches the public API, the changes have been approved in a separate issue with the "api-approved" label.
• The code complies with the Coding Guidelines for C#.
• The changes are covered by unit tests which follow the Arrange-Act-Assert syntax and the naming conventions such as is used in these tests.
• If the PR adds a feature or fixes a bug, please update the release notes with a functional description that explains what the change means to consumers of this library, which are published on the website.
• If the PR changes the public API the changes needs to be included by running AcceptApiChanges.ps1 or AcceptApiChanges.sh.
• If the PR affects the documentation, please include your changes in this pull request so the documentation will appear on the website.
  • Please also run ./build.sh --target spellcheck or .\build.ps1 --target spellcheck before pushing and check the good outcome

Legal checklist

• This work is entirely original, it is not derived from any existing code incompatible with the Apache 2.0 License, like FluentAssertions.