Replace deprecated declaration-property-unit-* rules

[tfrommen]

The declaration-property-unit-blacklist and the declaration-property-unit-whitelist rules have been deprecated, and should be replaced with declaration-property-unit-disallowed-list and declaration-property-unit-allowed-list, respectively.

This will be a breaking change, as user overrides won't work any longer, and therefore require a major version release.

References:

• https://github.com/stylelint/stylelint/blob/13.7.0/lib/rules/declaration-property-unit-blacklist/README.md
• https://github.com/stylelint/stylelint/blob/13.7.0/lib/rules/declaration-property-unit-whitelist/README.md

[tfrommen]

This is actioned in #248.

[ntwb]

This is now fixed via #248 & #275