changes unicode_utils version to 1.2.2

Previous versions of unicode_utils does not have [general_category.rb](https://github.com/lang/unicode_utils/blob/v1.2.2/lib/unicode_utils/general_category.rb) which is included in [sort_alphabetical.rb](https://github.com/grosser/sort_alphabetical/blob/master/lib/sort_alphabetical.rb#L4)