Log Message:
Update OOTools to version 2.21. This closes PR 31678 from Zafer Aydogan.

Changes from 1.75(doesn't include minor fixes):

Version 2.21
- Little documentation improvement

Version 2.2
- Added Package::props and Package::groups pragmas
- Added improved tests

Version 2.12
- Fixed the Class::Util::import function

Version 2.11
- Changed the Class::Util::classes function

Version 2.1
- Added the Class::Util::gather function plus tests
- Added the Class::Util::classes function plus tests
- Added the Class::Util::blessed function plus tests

Version 2.0
- Added the Class::Error module and tests
- Added the Class::Util module and tests
- Added the 'skip_autoload' option to Class::constr pragma
- You can also pass an HASH reference to the constr method

Version 1.79
- A test addition

Version 1.78
- The properties defined with a group get initialized just once
- Some testing addition and rewrite

Version 1.77
- Added 'default' option to the Class::constr pragma plus tests
- Added possibility to get a slice of values from groups accessors
- Added $_ aliasing for the post_process option

Version 1.76
- Added add_to() method to add props and groups accessors in other packages
- Added post_process() option to props accessors