small fixes for php 8.0

issue #37

1.1.2 Slugify bug fixed

• Prevent invalid range offset in slugify function

1.1.1 strong type cast

Fix bug with invalid strings

1.1.0

Remove support of php7.0 (now lib require php7.1+ to work), improve d…

…ocumentations, tests. fix bugs.

1.0.1

Added static alias for constructor

Stable release

Merge pull request #20 from fe3dback/optimizing

final fixes