v4.0.0

What's Changed

• Update to Cake 4.0 (@pascalberger)
• Multi-Target .NET 6, 7 & 8 (@pascalberger)
• Update to LibGit2Sharp 0.29.0 (@pascalberger)
• Introduce Cake.Frosting.Git addin for using with Cake Frosting (@pascalberger)
• Document steps to release new versions of Cake.Git (@augustoproiete)

Pull requests were reviewed by: @nils-a

Fixes issues reported by: @pascalberger @augustoproiete