update css dependency (#1037)

Task/Issue URL:  https://app.asana.com/0/0/1208077416568652/f
iOS PR: duckduckgo/iOS#3492
macOS PR:  duckduckgo/macos-browser#3415
What kind of version bump will this require?: Minor

**Description**: Updates C-S-S and adds privacy feature

Sources/BrowserServicesKit/PrivacyConfig/Features/PrivacyFeature.swift

@@ -62,6 +62,7 @@ public enum PrivacyFeature: String {
     case autocompleteTabs
     case networkProtection
     case aiChat
+    case contextualOnboarding
 }
 
 /// An abstraction to be implemented by any "subfeature" of a given `PrivacyConfiguration` feature.