Sparkle is a framework that is bundled within Mac apps, so it is likely in your Applications directory. You can get a list of applications with that framework using this Terminal command:
find /Applications -name Sparkle.framework
If you want to find out which app is causing this error, then you should check out each one and try to update it manually. Once you found it, you should check the developer’s website to see if a new version is available or report the problem to them.