Update `interactive.jl` notebook for new Pluto version

[fonsp]

• Make sure the @initially macro still works
• Save notebook file with new Pluto
• Dark mode support, this seems to work:

pluto-output img, pluto-output svg {
    filter: invert(1) hue-rotate(180deg) contrast(0.83) brightness(1.4);
}

• Update PlutoUI