Rename `color-adjust` to `print-color-adjust` to fix Autoprefixer deprecation warning

[Vheissu]

The W3 spec has deprecated the color-adjust property, but in its place added print-color-adjust which accepts the same values. As a result, in version of Autoprefixer 10.4.6 onwards, using MDB UI Kit will result in a deprecation warning and break builds with the warning. The fix is simple and I have done so in a pull request here.