2.2.1 (2022-02-11)
Fixed
* fixed Syntax version of absence groups ((?~...))
- the lexer accepted them for any Ruby version
- now they are only recognized for Ruby >= 2.4.1 in which they were
introduced
* reduced gem size by excluding specs from package
* removed deprecated test_files gemspec setting
* no longer depend on yaml/psych (except for Ruby <= 2.4)
* no longer depend on set
- set was removed from the stdlib and made a standalone gem as of Ruby 3
- this made it a hidden/undeclared dependency of regexp_parser
156b3c7173