Add d-spy icon

[ogarcia]

D-Spy is a simple tool to explore D-Bus connections.

Home page: https://apps.gnome.org/app/org.gnome.dspy/ Project repository: https://gitlab.gnome.org/GNOME/d-spy SVG Icon: https://gitlab.gnome.org/GNOME/d-spy/-/blob/main/data/icons/hicolor/scalable/apps/org.gnome.dspy.svg Icon name: org.gnome.dspy