appimage-run: Add libsecret for bitwarden

Previously running the Bitwarden AppImage would error.
This adds libsecret which resolves the error and allows the
Bitwarden AppImage to function normally.

pkgs/build-support/appimage/default.nix

@@ -205,6 +205,8 @@ rec {
       at-spi2-core
       pciutils # for FreeCAD
       pipewire # immersed-vr wayland support
+
+      libsecret # For bitwarden
     ];
   };
 }