Update music icon in dark mode for better visibility

[Lacplesis]

Problem

The current music icon looks fine on light mode, but once you switch to dark mode, it has far less contrast as compared to the other icons in Files.

Proposal

Consider updating the icon with a color and value that would be more consistent with the other icons and easier to see at a glance (purple or orange maybe?). Also, consider making the stems of the notes wide enough to have the same color running vertically to make the icon read better. I've attached a screenshot of Pop OS's music icon as reference for the thickness.

Prior Art (Optional)

[jeremypw]

Thanks for reporting but this is a duplicate of elementary/icons#853.