Project maintenance updates

[xperiandri]

Description

• Migrate to default .gitignore
• Updated Paket to 7.2.1
• Update Fantomas to 6.2.1
• Update FsDocs to 19.1.0
• Update .NET SDK on CI to 6.0.414
• Make .editorconfig more safe

• boy scout rule: "leave the code behind in a better state than you found it" (fix warnings, obsolete members or code-style in the places you worked in)
• Fake API guideline is honored

[Numpsy]

/home/runner/work/FAKE/FAKE> "dotnet"  fantomas src/app/ src/template/ src/test/ --recurse --check (In: false, Out: false, Err: false)
Unhandled exception. System.IO.DirectoryNotFoundException: Could not find a part of the path '/home/runner/work/FAKE/FAKE/--recurse'.

I think Fantomas 6 made the folder searching recursive by default, and deprecated the command line flag for it - so ---recurse can be removed from the invocation?

[Numpsy]

Is it worth updating Paket to v8 now, or leave that till later?

[xperiandri]

I would release this changes to v6 and then updated to v8