Set perl minimum version to 5.22 or 5.24

[shawnlaffan]

5.16 is several years old now, and using a more recent minimum perl version will enable wider usage of some of the recent enhancements.

For example, Perl 5.22 introduced refaliasing as a feature. This can speed up code that does a lot of dereferencing. It is already used in some places, but guarded by version tests, and resulting in multiple code paths that need to be maintained.

5.20 introduced subroutine signatures, and these were sped up in 5.26. They are currently experimental, but appear stable for the Biodiverse use case.

[shawnlaffan]

see also #659

[shawnlaffan]

Settle on 5.22. There is nothing urgent in 5.24. Any plan to use a more recent version can be a new issue.

CI failure is unrelated, mark as fixed.