Release 0.22.2

Released 2021-07-03. Progress: 4002 of 6180 tests passed in dart-sass compatibility mode.

• Changed the red(..), green(..), and blue(..) functions to always return integers. Issue #114, thanks @Keats.
• Changed the blackness(..) and whiteness(..) functions to return blackness/whiteness of the integer rgb approximations of the color rather than the exact color.