perlbrew install perl-5.42.0
perlbrew switch perl-5.42.0

##</code><code>##

ken@titan ~/tmp
$ perl -E 'use namespace::clean'

ken@titan ~/tmp
$ perl -v

This is perl 5, version 42, subversion 0 (v5.42.0) built for cygwin-thread-multi

Copyright 1987-2025, Larry Wall
...

##</code><code>##

ken@titan ~/perl5/perlbrew/perls
$ cp perl-5.40.0/lib/site_perl/5.40.0/namespace/clean.pm perl-5.42.0/lib/site_perl/5.42.0/namespace/clean.pm