fspy: mark insecure due to vendoring ancient Electron

Updating to use a newer version would require substantial upstream
changes, and upstream has no updates since 2020.

pkgs/applications/misc/fspy/default.nix

@@ -19,6 +19,7 @@ in appimageTools.wrapType2 {
     description = "A cross platform app for quick and easy still image camera matching";
     license = licenses.gpl3;
     homepage = "https://fspy.io/";
+    knownVulnerabilities = [ "Vendors Electron 2.0 (end-of-life)" ];
     maintainers = with maintainers; [ polygon ];
     platforms = platforms.linux;
     mainProgram = "fspy";