safari 12 upgrade

So my 2017 MBPro running High Sierra tells me I should upgrade to Safari 12. However, when I click the "Update"" button on the App Store Upgrade page, I get a notification that says this: “Safari” cannot be updated because its extensions are in use by “Spotlight”. Click OK and quit the application."

How do I "quit" Spotlight? It's not a regular app; it's part of System Preferences and, I think, is simply constantly running on its own. How do I get this upgrade?