Module::Build 0.4200 compatability

work around for this commit in Module::Build:

https://github.com/Perl-Toolchain-Gang/Module-Build/commit/044356d0e9934eaf45a9016786b6efa524cdf6f7

the license resource isn't converted from scalar to list as it should be when going from spec version 1 to 2.
Since the license is already specified as perl in the meta URL links to the text of the license is unnecessary