Fix gotchis mouth color.

[xibot]

All aavegotchi have now the mouth in black, and the correct color is the darker color of its collateral that is the gotchi body stroke.

i.e.
If collateral is UNI, gotchi mouth should be the dark pink/magenta color.
If collateral is LINK, gotchi mouth should be dark blue.
If collateral is USDT, gotchi mouth should be dark green.

:)