Slug Generator Versions Save

• Support PHP 8.0. [#23]
• Fix type issues found by PHPStan.
• Update fallback transform rule sets from CLDR.

• Add slug generator interface. [#11]

• Fix bug with intl error settings. [#13]

• Support lower ICU versions down to 4.2.1.
• Add changelog.

• Require minimum ICU version 4.6, #9
• Improve setting transforms in SlugOptions

ausi/slug-generator is now stable 🎉🎊

• Rename options to make them unambiguous