CI: Enable tvOS sample build
Fix
/Library/Frameworks/Mono.framework/External/xbuild/Xamarin/iOS/Xamarin.iOS.Common.targets(646,3): error : No valid tvOS code signing keys found in keychain. You need to request a codesigning certificate from https://developer.apple.com. [/Users/runner/runners/2.163.1/work/1/s/Samples/LibVLCSharp.tvOS.Sample/LibVLCSharp.tvOS.Sample.csproj]
in the CI, then revert fcecc3d8