Update Terminal.Gui requirement from 1.0.0.* to 1.1.1.*
Updates the requirements on [Terminal.Gui](https://github.com/migueldeicaza/gui.cs) to permit the latest version.
- [Release notes](https://github.com/migueldeicaza/gui.cs/releases)
- [Commits](https://github.com/migueldeicaza/gui.cs/compare/v1.0.0...v1.1.1)
Signed-off-by: dependabot[bot] <[email protected]>