Add a META.yml to the distribution. Your buildtool should be able to autogenerate it.
Add a README to the distribution. It should contain a quick description of your module and how to install it.
Remove the POD errors. You can check for POD errors automatically by including Test::Pod to your test suite.
Error: Math-Fibonacci-1.5/lib/Math/Fibonacci.pm -- Around line 122: You forgot a '=back' before '=head1'
Add a META.json to the distribution. Your buildtool should be able to autogenerate it.
Define the license if you are using in Build.PL. If you are using MakeMaker (Makefile.PL) you should upgrade to ExtUtils::MakeMaker version 6.31.
Add 'use warnings' (or its equivalents) to all modules (this will require perl > 5.6), or convince us that your favorite module is well-known enough and people can easily see the modules warn when something bad happens.
This is not a critical issue. Currently mainly informative for the CPANTS authors. It might be removed later.