[GUI] don't serialize current filter box contents into app config; it…

…'s confusing for this to persist across app runs

frontend/jgenesis-gui/src/app.rs

@@ -41,6 +41,7 @@ struct ListFilters {
     sega_cd: bool,
     nes: bool,
     snes: bool,
+    #[serde(skip)]
     title_match: String,
 }