Downgrade fatpacked CPAN::Meta

CPAN::Meta::Converter which is fatpacked by cpanm-1.7002
requires version 1.33 of List::Util, however that is a not core module,
thus cannot execute certainly on initial environment of Perl.
So downgrade CPAN::Meta to exclude dependency on List::Util.
Merge pull request #372 from moznion/downgrade_fatpacked_cpan_meta

Downgrade fatpacked CPAN::Meta